Discrete Event Simulation of the ATLAS Second Level Trigger

GB100-6Atlas SCRTriac and Thyristor AnalyserModel SCR100Designed and manufactured with pride in the UKUser Guide© Peak Electronic Design Limited 2004/2012In the interests of development, information in this guide is subject to change without notice - E&OEContents Page Introduction (3)Safety Considerations (4)Analysing components (5)SCRs (6)Triacs (7)Notes on SCRs (Thyristors) and Triacs (8)Gate Sensitivity (10)Gate Voltage (11)Care of your Atlas SCR (12)Battery Replacement (12)Self Tests (13)Appendix A – Accessories (14)Appendix B – Technical Specifications (15)Warranty Information (16)The Atlas SCR is an advanced instrument designed specifically for the analysis of SCR (Thyristor) and Triac devices. Summary Features:•Automatic component identification (Thyristor or Triac). •Automatic pinout identification.•Displays actual trigger (gate) current classification. •Measures gate voltage during trigger.•Fixed load current of 100mA.•Unique automatic boost function ensures a device test voltage of 12V regardless of battery condition. •Suitable for devices requiring gate currents up to 90mA. •Automatic and manual power-off.The Peak Atlas SCR is designed to analyse discrete, unconnected, unpowered components. This ensures that e xternal connections don’t influence the measured parameters. The three test probes can be connected to the component any way round.The Atlas SCR will start component analysis when the on/test button is pressed.The analysis typically takes less than a second to complete, after which the results of the analysis are displayed. Information is displayed a “page” at a time, each page can be displayed by briefly pressing the scroll/off button.If the Atlas SCR cannot recognise the component connected to the test probes, or the component under test is outside the specifications covered by this instrument, the following message willbe displayed:Note:The arrow symbol on the display indicates that more pages areavailable to be viewed.The unit will switch off automatically after a period of inactivity, however the unit can be switched off manually too by pressing and holding the scroll/off button for around 1 second.The Atlas SCR will analyse almost any SCR provided that a gate trigger current of no more than 90mA is required.The three test clips can be connected to the device under test any way round. If the Atlas SCR detects an SCR, the following message will be displayed:Pressing the scroll/off button will then display the pinout details for the device.In this example, the Anode of the SCR is connectedto the Red test clip, the Cathode is connected to the Green test clip, and the Gate terminal is connected to the Blue test clip. The gate trigger current is displayed on the next screen.Note that SCRs are often only specified to have a certain maximum trigger current – the actual (tested) triggercurrent may be well below that value.AKGThe Atlas SCR will analyse almost any Triac, provided that it requires a gate trigger current of no more than 90mA. The three test clips can be connected to the device under test any way round. If the Atlas SCR detects a Triac, the followingmessage will be displayed:Note: The device under test will be analysed in quadrants 1 and 3. The definition of these quadrants is given later in this guide.Pressing the scroll/off button will then display the pinout details for the device.In this example, the MT1 terminal of the Triac is connected to the Red test clip, the MT2 terminal is connected to the Green test clip, and the Gate terminal is connected to the Blue test clip. The gate trigger current is displayed on the next screen. Note that Triacs are often onlyspecified to have a certain maximumtrigger current – the actual (measured) trigger current may be well below that value.The gate trigger current 1 displayed is that for quadrant 3. (Quadrant 1 will usually be very similar).The load current at which the Triac was tested is also displayed. This value is fixed for all devices, and simply serves as a reminder. The symbol indicates that this is the final page of information. Pressing the scroll/off button again will return the display to the first page of information.Note 1. See the “Gate Sensitivity” section later in this guide.M T 2M T 1GSilicon Controlled Rectifiers (Thyristors)SCR Turn-OnSCRs (Thyristors) act as a controlled diode. They block reverse current at all times, and they conduct in the forward direction only when triggered by a pulse of current to the control (gate) terminal. Once triggered, the SCR will continue to conduct current in the forward direction until the device is turned off.SCR Turn-OffIn order to turn off a triggered SCR, it is necessary to reduce the main terminal current below the holding current for typically 5-200 S. Shorter periods may leave insufficient time for free charge carriers to recombine, and thus when main current is reapplied, the device may remain triggered.TriacsTriacs are a well established technology, designed specifically for the solid-state control of AC loads. They offer bi-directional load current switching (for both half cycles of the mains supply) and also bi-directional gate current capability to trigger the device. The combinations of the load currents and gate control currents are referred to as “quadrants”. These quadrants are shown below:The main load current ishandled by the connectionsMT1 and MT2. The device isswitched to the on state by acurrent into (or out of) thegate terminal with respect tothe MT1 terminal.Once triggered, main loadcurrent will continue to flowuntil a zero-cross in themains cycle is encountered,at this point the deviceswitches off. Therefore, if thedevice is to be kept on, acontinuous gate current mustbe provided or at least a gatecurrent pulse that occurs immediately after each mains zero-cross.Many triacs however are only capable of operating reliably in 3 of the 4 quadrants. (In particular, Q1, Q2 and Q3). Quadrant 4 (negative gate current and negative load current) can be troublesome with some triacs, suffering from poor gate sensitivity and slow response.The Peak Atlas SCR attempts to trigger the device under test at nine discrete gate currents, in ascending order.As an example, a reported trigger current of 10-25mA means that device triggering occurred at a gate current of 25mA, but not at 10mA. Therefore the trigger current for the device under test is between 10mA and 25mA. Although Triacs are tested in both quadrants 1 and 3, the reported gate trigger current is that which applies to quadrant 3.Gate VoltageIf the Atlas SCR has successfully tested a triac or thyristor, it will be able to display the gate voltage as well as the gate sensitivity.The gate voltage is the voltage measured across the gate and the cathode (for a thyristor) or across the gate and MT1 for a triac. The voltage is measured during the time that the device under test has actually triggered.An example of the displayed value is shown here:Note that the gate voltage is measured at the upper end of the displayed gate trigger current.For example, if the gate sensitivity is shown as 35 to 50mA, then the displayed gate voltage will be the voltage measured during a gate current of 50mA.The gate voltage may also be dependent on the load current, for the Atlas SCR , the load current is fixed at 100mA, higher load currents may result in a higher gate voltage.The load current at which SCRs and Triacs are tested is displayed. This value is fixed for all devices, and simply serves as a reminder.The symbol indicates that this is the final page of information. Pressing the scroll/off button again will return the display to the first page of information.The Peak Atlas SCR should provide many years ofservice if used in accordance with this user guide. Care shouldbe taken not to expose your unit to excessive heat, shock or moisture. Additionally, the battery should be replaced at least every 12 months to reduce the risk of leak damage.As battery voltage falls over time, the automatic boost function will ensure that the test voltage is maintained at 12V. Forprogressivelylowerbattery voltagesthe boost function willtakelonger to achieve the target of 12V and the following may be displayed:If the boost function cannot generate the required test voltage then the following message is displayed:Replacement of the battery is then mandatory. The Atlas SCR will not continue to operate if this condition is encountered.New batteries can be purchased from many retailers and directly from Peak Electronic Design Ltd or an authorised agent.Battery types: Suitable battery type is Alkaline AAA or LR03 (1.5v). Rechargeable batteries or Zinc-Carbon batteries are not recommended.Battery access: To replace the battery, unscrew the three screws to remove the rear panel. Remove the old battery and insert a new one, taking care to observe the correct polarity. Carefully replace the rear panel, do not over-tighten the screws.Peak Safe Battery Disposal Scheme : Please return your old analyser battery to Peak Electronic Design Ltd for safe and environmentally responsible disposal.Each time the Atlas SCR is powered up, a self test procedure is performed. Inaddition to a battery voltage test, the unit measures the performance of many internal functions such as the voltage and current sources, amplifiers, analogueto digital converters and test lead multiplexers. If any of these functionmeasurements fall outside tight performance limits, a message will be displayed and the unit will switch off automatically.If the problem was caused by a Array temporary condition, such as applyingpower to the test clips, then simplyrestarting the Atlas SCR may clear theproblem.If a persistent problem does arise, it is likely that damage has been caused by an external event such as excessive power being applied to the test clips or a large static discharge taking place. If the problem persists, please contact us forfurther advice, quoting the displayed fault code.A range of useful additions is available to enhance your Atlas SCR.Carry CaseA specially designed case with custom made foam compartments and a smart tough exterior is ideal for protecting your Atlas SCR and probes. There is even space for a spare battery.Replacement ProbesIf your probes become damaged, you may wish to purchase a new set of probes.Replacement BatteryReplacement batteries are available from Peak Electronic Design Limited, your agent or any good electronic store.All accessories are available from Peak Electronic Design Limited or an authorised agent.1.Between any pair of test clips.2.For battery voltage greater than 0.9V.3.Subject to acceptable LCD visibility.Atlas SCR User Guide April 2012 – Rev 6Peak Satisfaction GuaranteeIf for any reason you are not completely satisfied with the Peak Atlas SCR within 14 days of purchase you may return the unit to your distributor. You will receive a refund covering the full purchase price if the unit is returned in perfect condition.Peak WarrantyThe warranty is valid for 24 months from date of purchase. This warranty covers the cost of repair or replacement due to defects in materials and/or manufacturing faults.The warranty does not cover malfunction or defects caused by:a)Operation outside the scope of the user guide.b)Unauthorised access or modification of the unit (except for batteryreplacement).c)Accidental physical damage or abuse.d)Normal wear and tear.The customer’s statutory rights are not affected by any of the above.All claims must be accompanied by a proof of purchase.At Peak Electronic Design Ltd we are committed to continual product development and improvement.The specifications of our products are therefore subject to change without notice.© 2004-2012 Peak Electronic Design Limited - E&OEDesigned and manufactured in the UK Tel. +44 (0) 1298 70012 Fax. +44 (0) 1298 70046。

Unit1 Free Falling1. What is the main subject introduced in paragraph one?It is the description of the effect of saying farewell to his parents, friends and folks on the author.2. How is the story organized?The story is chronologically organized (following the time sequence in which the event unfolded itself).3. How did Weckerly feel before the day of his departure?He felt eager and excited to wait for the day to come.4. How did his mood change when the day had really come?At the very beginning he became sentimental about saying good-bye to many people around him. Facing the reality of becoming independent, he began to feel afraid and uncertain .5. What do you think about the ending of the story?It is very impressive. Weckerly ends the story with a metaphor which catches the essence of the particular moment accurately. He compares himself to a rookie skydiver preparing for his first plunge, which leads to possible outcomes: sheer excitement or eventual death. The last sentence "He closes his eyes, takes a deep breath, and jumps" symbolizes the fact that from that day on the author jumps into the future of being independent no matter how long and complicated the road to it is.What is the effect of saying farewell and actual leaving on the author?Whom did the author like to say good-bye to? What was the author's mood like before the day of departure and after?How did his mother's mood change during his brunch with her?What was the significance of the particular day to the author?Suggested SummaryThe time of saying good-bye and actual leaving makes a great impact on the author, which is fully demonstrated in the opening sentence. He gives a general description of how he feels on that particular day, during which his own mood changes from sheer excitement for the prospect of becoming independent and free to fear and uncertainty to a mixture of both. By his brunching with Mom and saying good-bye to her, he makes a very smooth depiction of the change of his mother's mood from being chatty and cheerful at the beginning to being quiet, even somber as the final moment comes. To bring the story to its climax, the author ends the story with a symbolic description. He compares himself to a rookie skydiver preparing for his first plunge that leads to possible outcomes: sheer excitement or eventual death. No matter what will happen, he closes his eyes, takes a deep breath and jumps into the future.Unit2 The New Economics of Oil1. Why won't oil prices rise at all over the long time?Firstly, because producers need the cash from oil too much to let their supply be interrupted for long. Secondly, and more important, because demand growth can't push prices upward as long as it is balanced by supply growth.2. Why can't the members of the OPEC raise oil prices?Because if they do, non-OPEC sources will grab market share by developing fields where technology has made production affordable.3. Why have most majors cut their costs on oil?Because technology lets the companies maintain healthy earnings at steadily lower oil prices.4. Who takes a lead in the oil companies?Those that master technology and efficiency, such as Shell, Exxon, and British Petroleum.Should we worry about the oil price?What is the main reason for oil price to fall?Is Rainwater's high-price theory right?What influences oil industry profits most?How will lower oil price influence the world economy?Suggested SummaryThe article aims at establishing the idea that oil price will not rise even as demand soars. To begin with, the author shows the increasing consumption of oil around the world and the impact of technology on oil industry. By giving several examples, he draws the conclusion that the need for cash and dependence on technology leads to the fact that oil prices will even fall. Furthermore, technological updating, slashing the costs of finding, producing, and refining oil, is also a reason to support the author's point. There is evidence that technology lets the world companies maintain healthy earnings at lower oil prices. In conclusion, cheap oil accelerates the world economy, and a downside price scenario is increasingly likely.1. In the first year of peace, Lebanon's GDP soared by almost 40%. (C)A. flewB. hoveredC. increasedD. decreased2. SAIC's previous skirmishes with investigators had attracted little attention. (D)A. conflictsB. strugglesC. skatesD. arguments3. The boy grabbed hold of my bag and disappeared quickly into the crowd. (C)A. seizedB. snappedC. snatchedD. sneaked4. Although Chicago has fared better than some cities, unemployment remains a problem. (A)A. got onB. chargedC. offered jobsD. provided welfare5. The dwarfs were devastated, because they could not figure out how to save Snow White this time. (D)A. calculateB. rateC. considerD. decide6. His distrust of the power of critics made him ready to gibe at David Sylvester. (A)A. laughB. ridiculeC. derideD. taunt7. Children are most vulnerable to abuse within their own home. (A)A. unprotectedB. sensibleC. susceptibleD. harmful8. Short of the President himself, probably no one could have put the American case more persuasively. (B)A. Rather thanB. Other thanC. Less thanD. Short forUnit7 Competition Is Destructive1. Why is competition destructive according to the author? (para. 3)According to the author, competition is destructive because it undermines self-esteem, poisons relationships and holds us back from doing our best.2. What are the purposes of the games devised or collected by Orlick and others? (para. 6)The idea of the games devised or collected by Orlick and others is for each person on the field to make a specified contribution to the goal, or for all the players to reach a certain score, or for everyone to work with their partners against a timelimit.3. What is the difference between teamwork and team competition? (para. 8)The difference between teamwork and team competition is that in teamwork everyone on the field is working together for a common goal, while in team competition a given player works with and is encouraged to feel warmly toward only half of those present.4. Why do most kinds of fun require competition? (para. 10, 11, 12)First of all, people don't know any other way or people have never tasted the alternative.Secondly, we overlook the psychological costs of competition: it causes self-doubt and feelings of self-worth become dependent on external sources of evaluation.5. Who is to blame for competition?It is the structure of the game itself that is to blame rather than the individuals, since it sets competition at the very beginning.Directions: Use the questions given below as a guide to write a summary. You can refer to Task 1 and Task 2.What kind of games does the author use to illustrate the points?What's the significance of changing an "opponent" into a "partner"?What's the difference between teamwork and team competition?What are the possible reasons that a large number of people insist that we can't do without win/lose activities?What is the real problem?Suggested SummaryBy using the game of musical chairs, the author illustrates that competition is destructive not only in our daily work but also in entertainments. It is important and possible to change the form of the game by way of turning an opponent into a partner: Everyone on the field can work together for a common goal (teamwork) instead of competing with each other (team competition). Cooperative games and sports provide satisfaction and challenge without competition. The reason that a large number of people insist that we can't do without win/lose activities are that they don't know any other way and that they overlook the psychological costs of competition and the toxic effect of competition on our relations. Competition is not conducive to trust and it may lead one to look at others through narrowed eyes and even invite outright aggression. We are inclined to blame individuals for all this, but it is the structure of the game itself which causes competition. To solve the problem of competition, we need to be teaching our children how to enjoy themselves without competition.Identify one of the four choices A, B, C or D which best keeps the meaning of the underlined word or phrase.1. She has been eliminated from the swimming race because she did not win any of the practice races. (C)A. got outB. taking awayC. got rid ofD. driving away2. One of the major flaws in the existing system is that the prosecutor has immunity from law suits claiming malicious prosecution. (B)A. usefulB. spitefulC. harmlessD. cheerful3. They define a good patient as one who accepts their statements and their actions uncritically and unquestioningly. (A)A. characterizeB. confineC. fixD. limit4. Roberts' poor physical condition combined with nagging injuries prevented him from playing more than 51 games in the past four seasons. (A)A. troublingB. followingC. complainingD. accompanying5. Constant correction by a teacher is often counterproductive, as the student may become afraid to speak at all. (C)A. evilB. not productiveC. unfavorableD. hurting6. For centuries we women have gloated over the one negative aspect of aging more evident in men than women: balding. (B)A. praisedB. felt maliciously satisfied withC. felt sorry forD. expressed great pleasure of7. In the conducive atmosphere around the fort, General Bradley immediately found out about the plot. (D)A. goodB. suitableC. fitD. favorable8. It's a story of a harmful dynamic between white prejudice and black autonomy.(C)A. state of movementB. political forceC. competing or conflicting systemD. social system9. Gandhi rejects outright claims made concerning the superior or inferior status of religions. (B)A. ovreallB. directC. obscureD. ambiguous10. My first boss was a really nasty person, who seemed to enjoy making life difficult for everyone. (C)A. graveB. sorrowfulC. uglyD. pitifulUnit8 Power to the People1. What is the author's attitude towards alternative energy?The writer believes that alternative energy will play more important roles in the future.2. What advantages does PV have?It has the simplest and most elegant technology to harness the power of the sun, being easy to install and requiring minimal maintenance.3. What advantages does hydropower have?It is a clean, renewable source of energy that offers cheap electricity.4. What are the main disadvantages of wind power?Noise, negative impacts on local tourism, potential disruption to wild life.5. Why are fuel cells considered "zero emission" and preferred by some governments?They release only water vapour into the atmosphere. They are economical and require little maintenance as well as no recharging.Summarize the text.What will be the main means to power our modern societies?Why is it so urgent to find alternative energy?What is the future of solar power, wind power and hydropower?What are the final solutions to man's energy needs?Suggested SummaryIn the article "Power to the People", the author Mark Townsend states that solar power, wind turbines and other sources of clean power are now prepared to take the place of fossil fuels and become the main means to power our modern societies. He lists two reasons contributing to man's hot pursuit of alternative sources of energy. One is the environmental deficiencies of fossil fuels. Another is the crucial progress made by using new technology. According to the writer, a new generation of wafer-thin photovoltaic solar panels will lead to a great future of the solar energy. In addition, if the strength of rough seas can be brought under control, water power is likely to be another major renewable energy. Thirdly wind power can also benefit our life if we can eliminate the negative impacts on the environment. Finally, the author assumes that as an ideal clean energy, fuel cells will be the answer to the future energy needs.Identify one of the four choices A, B, C or D which best keeps the meaning of the underlined word or phrase.1. At the press conference, they were scrambling to give the impression that the situation was in control. (B)A. searchingB. strugglingC. crowdingD. exciting2. Written off again and again, he has proved phenomenal in resilience and political craftiness. (C)A. notableB. tangibleC. extraordinaryD. sensible3. This news has sent a wave of panic through the world which to me seems way out of proportion. (A)A. farB. meanC. simplyD. away4. Downtown business owners say they want the city's homeless shelter moved to a less conspicuous location. (D)A. confrontedB. fantasticC. confidentD. noticeable5. Over the past year, Linux has made significant inroads into embedded designs requiring rich, high performance networking. (C)A. made moneyB. made achievementsC. made advancesD. made progress6. The important thing is to harness growth to self-knowledge, a ready acceptance of change, swift-moving business practice and sound judgment. (B)A. make useB. controlC. produceD. escape7. We are the ones willing and able to run an obstacle course filled with hurdles that we must complete before anyone else. (A)A. barriersB. blessC. reportsD. handouts8. I haven't been able to orient my ideas to the new conditions since I worked abroad three months. (B)A. changeB. adjustC. directD. organize9. The company office was inundated with telegrams of congratulations on the tenth anniversary of its foundation. (B)A. overjoyedB. floodedC. crowdedD. satisfied10. He had drawn a contradictory conclusion in his thesis because he pinned hisfaith on an absurdity. (D)A. decidedB. practicedC. dependedD. placedUnit11 London Bridge Is Falling DownAnswer the following questions briefly according to the text.1. Why the Millennium Bridge was shut down soon after it had opened to the public?FeedbackBecause it kept vibrating when people walked on it.2. What happened to the Internet?The Internet became paralyzed due to many attacks made by anonymous hackers.3. Why was the Steamboat Act not established until 1838?This was due to two major causes. First, people did not figure out what caused the explosion of the steamboat until 1837. Second, the government did not attach enough importance to the problem.4. What does the congressman mean by saying "Let the Government attend to its own business, and let the people attend to theirs."?The congressman means it is the people's duty but not the government's to set standards for producing, maintaining and inspecting steam boilers.5. What's the author's opinion of the high-tech crises?Though the high-tech crises are inevitable, humans will always look for ways to tackle them and will never give up exploring into the unknown fields of science.Summarize the text.What have gone wrong with some new high-tech innovations?What is the writer's opinion of these high-tech crises?Why does the writer review the establishment of the Steamboat Act?How do people deal with technical trouble now?Will people continue to make attempts at new technologies in the future?Suggested SummaryBy highlighting two technological crises, i.e. the swaying Millennium Bridge and the crippling Internet, the writer successfully draws the readers' attention to the somewhat embarrassing problems with some new high-tech innovations. The writer argues that these crises are inevitable because the innovations lead us into the unexplored world of science. With a look back on the establishment of theSteamboat Act, the writer indicates that the improvement of any high-tech innovation will go through a long and slow process. Fortunately, we are now able to respond more quickly to the danger of new technologies, and have becomeincreasingly skilled in controlling the crises. In the end, the writer claims with confidence that humans are certain to defeat any catastrophe, and will never stop exploring the unknown technical world.Identify one of the four choices A, B, C or D which best keeps the meaning of the underlined word or phrase.1. Instead, he concentrates on how he helped raise Clinton from the dead after the debacle of the 1994 congressional elections. (C)A. disputeB. triumphC. catastropheD. deception2. She is running-running away from a shaking house and a row of wobbling green trees. (B)A. swervingB. swayingC. steeringD. striding3. A total of 252 imported pests have been spotted, of which 174 could wreak havoc on forests. (A)A. inflictB. inflateC. preventD. relieve4. But no evidence suggests that she courted danger for her children as she encouraged their freedom. (B)A. ignoredB. provokedC. flatteredD. avoided5. The report explains the gruesome results the weapons will have on human beings. (D)A. seriousB. furiousC. pleasingD. shocking6. Residents are bracing themselves for further carnage caused by the typhoon. (B)A. cargoB. damageC. suicideD. assassination7. The biggest threats to children's health lurk in the very places that should be the safest-at home, in school and the community. (D)A. fleeB. lureC. sneakD. hide8. Vigilance against collateral environmental damage is crucial to sustainable growth nowadays. (D)A. neglectB. suspicionC. indignationD. caution9. Racism has many forms. It does not solely manifest itself against one particular race. (C)A. testifyB. verifyC. showD. conceal10. The child has a very responsive nature and will soon become fond of you. (A)A. sensitiveB. silentC. introvertD. lively。

July, August, September 2013Page 1 The Simulation StandardINSIDE2D IBC-SHJ Solar Cell Simulationand Optimization ...................................................12Continued on page 2 ...Volume 23, Number 3, July, August, September 2013Validation of the model has been carried out in Atlas and Victory Device based on [1,2] and simulation results for an AlGaN/GaN structure as shown in Figure 1 and 2.Mobility and impact Ionization models are also GaN-specifi c. You can use a composition and temperature dependent low fi eld model by specifying the FMCT.N and FMCT.P in the MOBILITY statement. FMCT stands for Farahmand Modifi ed Caughey Thomas. This model was the resultFigure 1. comparison of the built-in piezoelectric model betweenAtlas and Victory Device.The Simulation Standard Page 2 July, August, September 2013 of fi tting a Caughey Thomas like model to Monte Carlodata [3]. You can also choose to model low fi eld mobilityas a function of doping and temperature following thework of Albrecht et.al [4] by specifying ALBRCT on theMODEL statement or ALBRCT.N or ALBRCT.P or bothon the MOBILITY statement for separate control overelectrons and holes. You can fi nally select the nitride-spe-cifi c high fi eld dependent mobility model by specifyingGANSAT.N and GANSAT.P on the MOBILITY statement.This model [3] is based on a fi t to Monte Carlo data forbulk nitride and exhibits negative differential mobilityas shown in Figure 3.As far as Impact Ionization is concerned, using the tabu-lar Selberherr model, we provide build-in tabular rep-resentations of results from several recent publications.We provide convenient access using different key wordson the IMPACT statement. Figure 4 shows a comparisonof the various tabular ionization rate models against thedefault models.Performance of GaN devices can be altered by the pres-ence of defects (traps and intraps) and also by self heat-ing. It is thus important to take these effects into ac-count during simulation. Our simulators allow 2D and3D simulation of self heating effects. Models includeheat generation, heat fl ow, lattice heating, heat sinks,and effects of local temperature on physical constants.Thermal and electrical physical effects are coupledthrough self-consistent calculations. IV characteristicsare not always reproductible as a result of deep traps inthe nitride material. A deep trap may be regarded as animpurity or crystal defect that captures a mobile chargecarrier and keeps it strongly localized in the neighbor-hood of the trapping center. Deep traps can producecurrent collapse, a distortion of the device current-volt-age (I-V) characteristic that is of particular concern be-cause it ultimately limits the output power of the device.Discrete and continuous Traps and Interface traps areavailable in Atlas and Victory so that these effects can betaken into account.The main concept of GaN-based power devices is to useepitaxial strain to create 2DEG. As mentioned above weprovide a built-in model for that. On top of that, thisbuilt-in model also supports dependency on a loadedstrain tensor resulting for example from a depositedstress-liner made of nitride on top of the AlGaN/GANlayers. The “intrinsic” stress resulting from this nitridelayer is computed using Victory Stress and can be direct-ly loaded in Atlas or Victory Device.ApplicationsIn this section we will review and show 2D and 3D simu-lations of different type of structures. We will comparesimulation results with experiments and show differenttype of simulations including DC, Transient, AC andlarge signal.Figure 2. Sheet carrier concentration versus alloy compositionand thicknesses.Figure 3. Velocity-fi eld curves for pure GaN for various low-fi eld.Figure 4. Comparison of electron ionization rates as a function ofreciprocal fi eld with extrapolation enabled.July, August, September 2013 Page 3 The Simulation Standard A Normally-off GaN MISFET withHigh Vth uniformityThis example demonstrates the simulation of a GaN met-al-insulator-semiconductor fi eld effect transistor (MIS-FET) with Piezo Neutralization Technique (PNT) [5].The fi rst feature of the PNT structure is an AlGaN bufferlayer to realize a normally-off operation. The polariza-tion charges at the interface between the AlGaN bufferand the GaN channel act as virtual p-type doping andcontribute to simultaneously increase Vt and charge den-sity in the channel. The band diagram and IdVg shownin Figure 5 and in Figure 6 respectively demonstrate theimpact of the buffer Al-concentration on the electron-channel energy beneath the gate and Vth respectively.The second feature is an Al0.07Ga0.93N PNT layer havingan identical Al composition with the buffer layer to realizehigh Vth uniformity. Since PNT and buffer layers have anidentical Al mole fraction, the polarization charges formedbetween these layers are completely canceled, and hence afl at band condition occurs throughout the PNT layer.Vth dependence on the AlGaN layer thickness under thegate electrode was simulated. For the GaN FETs with thePNT structure, the Vth is not affected by the variation ofAlGaN thickness whereas it varies for the conventionalAl0.15Ga0.85N/GaN single heterojunction FETs as asshown in Figure 7.The last feature is the second supply layer at the region out-side the gate electrode to reduce on-resistance of the GaNFET. Since the second supply layer is consisted of AlGaNwith higher Al composition than that for the fi rst supplylayer, a large amount of 2DEG is produced both in the chan-nel layer and the PNT layer as shown in Figure 8.A Normally-off GaN HFET with p-type GaN gateThis example demonstrates simulation of a GaN HFETwith p-type GaN gate [6] shown in Figure 9.While a Schottky-type metal on the AlGaN barrier actsas a gate for normally-on HEMTs, a p-type doped semi-conductor gate is able to deplete the transistor channel Figure 5. Conduction band energy under the gate versus AlGaNx composition.Figure 6. IdVg curves as a function of AlGaN x composition.Figure 8. Polarization charge concentration outside the gateregion in the PNT structure.Figure 7. IdVg curves from conventional and PNT structures withdifferent AlGaN thickness.when unbiased, thus yielding a normally-off device. The simulation of the transfert characteristic reveals a Vt of around 1.25V. The sub-threshold leakage current drops signifi cantly immediately below the threshold voltage, however the drop slows down to around 4uA/mm at VGS=0V. The leakage current is determined by traps. The gate current in the on-state (defi ned as VGS=5V) is around 3uA/mm and thus around fi ve orders of magni-tude below the drain current as as shown in Figure 10. The output characteristic shows a negative differential resistance due to lattice heating and simulated by solv-ing the lattice heating equation The maximum drain cur-rent is approximately 0.4A/mm as seen in Figure 11. The Breakdown Voltage of this device is 870V as seen in Figure 12 , and the leakage current is controlled by the traps.Enhancement-Mode N-Polar GaN MISFETsThis example demonstrates simulation of an Enhance-ment-Mode N-Polar GaN MISFET [7]. The structure is shown in Figure 13. There is a growing interest in high performance enhancement mode GaN channel devices because of single voltage operation and simpler cir-cuit topologies. The advantages of enhancement mode GaN FETs fabricated on N-polar GaN include reduced source/drain access resistance and wide bandgap barri-er layers used for a polarization-induced fi eld allowing 2DEG depletion under the channel. Removal of the AlN layer from the access region recovers the 2DEG induced by the bottom AlN layer. Plots of the bang diagram un-der the gate and under the nitride sidewall reveal 2DEG under the access region but not under the gate as seen in Figure 14.Figure 10. GaN HFET with p-type GaN gate drain and gate current versus gate voltage.Figure 11. GaN HFET with p-type GaN gate drain current versus drain voltage.Figure 12. GaN HFET with p-type GaN gate breakdown voltage simulation.Figure 9. GaN HFET with p-type GaN gate.The Simulation Standard Page 4 July, August, September 2013July, August, September 2013 Page 5 The Simulation Standard The simulation of the transfert characteristic reveals a Vtof around 1V and a maximum Ids of around 0.7A/mm atVgs=5V as seen in Figure 15.Electron injection from the channel to the gate is limitedby the AlGaN/GaN heterojunction. As a consequence nocurrent offset is observed at zero drain since gate currentis very low. This device exhibit a threshold voltage around1V, a maximum drain current at Vd=10V and Vg=5V of200mA/mm and a breakdown voltage of 640V as as shownin Figure 17, Figure 18 and Figure 19 respectively.Figure 13. Enhancement-Mode N-Polar GaN MISFETs.Figure 14. Bang diagram under the gate, under the nitride sidewalland under the drain regions.Figure 15. Drain current versus gate voltage.Normally-off AlGaN/GaN Transistor withConductivity ModulationThis example demonstrates simulation of a normally-offAlGaN/GaN transistor with conductivity modulationresulting from hole injection from a p-AlGaN gate tothe AlGaN/GaN heterojunction [8]. The p-AlGaN gateallows normally-off operation.When the gate voltage increases and reaches the built-inpn junction voltage at the gate (around 3.5V) holes injectinto the channel and generate the equal number of elec-trons increasing the 2DEG. Electrons with high mobilitywill reach the drain under the effect of the electric fi eldwhereas the holes will stay since their mobility is muchlower than the electron. The current is thus modulatedby the number of holes injected. It is also interestingto notice that this device exhibits a double peak in thetransconductance curve, a second proof of hole injectionas as shown in Figure 16.Figure 16. Transconductance versus gate voltage.The Simulation StandardPage 6July, August, September 2013Fe Bulk Doping Related Current Collapse PhenomenonThis example demonstrates simulation of the “Current Collapse” and “Current Recovery” phenomenon result -ing from population and de-population of Intentional Iron (Fe) Doping Traps under the gate of a GaN FET as a result of Gate to Drain Electric Fields.Many publications suggest that unintentional surface traps are the main cause of the GaN current collapse phenomenon. In this example, we show that some -times this is not actually the case. Current collapse in this device is mostly caused by intentional iron dop-ing, whose main purpose is to create a semi-insulating buried layer to reduce the buried layer source-to-drain leakage path.The device structure in this example is based on [9].Substrate leakage current is controlled by a graduated concentration of deep level iron acceptor traps located 1eV below the conduction band edge.The device is first biased with 0v on the gate and 5v on the drain. After a mili-second at this bias, the device is field stressed for only one further milli-second at 25v on the drain and -4v on the gate as seen in Figure 20. After this short bias stress, the device was returned to its origi-nal bias of 0v on the gate and 5 volts on the drain. After only one milli-second of bias stress, the drain current is significantly reduced demonstrating the current collapse phenomenon as seen in Figure 21.Figure 18. Drain current versus drain voltage.Figure 19. Breakdown voltage characteristic.Figure 20. Gate and drain voltage biases.Figure 21. Current collapse simulation result.Figure 17. Drain current versus gate voltage.July, August, September 2013Page 7The Simulation StandardA comparison structure file plot of the pre and post-stress ionized Fe trap density shows that the cause of the current collapse is actually the change in charge state of the Fe doping deep in the substrate under the gate, and also on the drain side between the gate and drain con-tacts as seen in Figure 22.stress distributions via the stress-liner made of nitride as shown in Figure 24 and Figure 25. Note that the stressor in this example is used to illustrate strain polarization on top of piezo and spontaneous polarization.Figure 22. Pre and post stress ionized Fe trap density.Figure 23. Device recovery simulation.Figure 24. 3D AlGaN/GaN HEMT.Figure 25. Strain XX generated by a stress-liner made of nitride.Figure 26. Drain current versus gate voltage for ore and post-stres device.For completeness, the unstressed bias remained on the device until the traps became de-populated with elec-trons and the drain current returned to its original val-ue. Interestingly, it takes over one week for the device to recover. (6e5 seconds) as seen in Figure 23. This very long recovery time may be incorrectly interpreted as de-vice degradation from field-induced traps which is an irreversible effect resulting from electric field-induced reverse piezo-electric stress.2-6 3D AlGaN/GaN HEMT Including Intrinsic Stress EffectThe device under consideration is a 3D AlGaN/GaN HEMT shown in Figure 24. 3D stress distribution is simulated by Victory Stress. This example producesThe Simulation Standard Page 8 July, August, September 2013After the initial solution is obtained, the drain voltage is ramped to 1 V, then the IdVg characteristic is extracted from Vg=-8 to Vg=1.0 V as seen in Figure 26. The effect of strain is seen on IdVg. Overlay of 2D simulation results with 3D simulation results obtained with width=1 vali -dates our 3D implementation.Influence of the Gate to Drain distance on the break -down voltageThis example demonstrates the influence of the gate-to-drain distance on the breakdown voltage with and with-out silicon substrate [10]The structure consists of 20nm AlGaN with xcomp=0.2 and 1um GaN buffer layer as as shown in Figure 27. Do -nor and acceptor traps are included in the simulation. Gaussian profile acceptor traps are used with a peak concentration close to the bottom of the buffer layer to mimic the fact that the material quality improves toward the surface of the device.Donor Interface traps at the AlGaN/Nitride interface and acceptor interface traps at the GaN/Silicon interface are also included during the simulation.Forward characteristic simulation reveals a threshold voltage of around -2V. Slow transient simulation is used to simulate the breakdown voltage curve.The deck is parametrized so that we can vary the dis -tance between the gate and drain (LGD). DeckBuild DoE capability is used to automate simulations of BV versus LGD with and without substrate.We can observe in Figure 28 an almost linear increase of BV versus LGD when silicon substrate is not present. An increase of the gate current is observed in Figure 29 near breakdown, and the value is of the same order as the drain current. This result indicates that BV is defined by an avalanche phenomenon between the gate and the drain as shown in Figure 30.BV does not depend significantly on LGD when a silicon substrate is present due to charge accumulation at the GaN/Silicon interface, related to the presence of inter-face traps, which screen the electric field.Figure 27. AlGaN/GaN HEMT with and without Silicon substrate.Figure 28. BV versus LGD with and without silicon substrate Fig -ure 29 Drain and gate current versus drain voltage.Figure 29. Drain and gate current versus drain voltage.Figure 30. Potential distribution as a function of LGD distance.July, August, September 2013Page 9The Simulation StandardGaN HEMT Thermal Optimization using Flip Chip StructureThis example demonstrates two-dimensional electro-thermal simulations with heat sink structures.Although the superiority of GaN HFET device character -istics has been demonstrated, the self heating effect has hindered the production of high power and high speed GaN-based switching devices. This effect can be signifi -cantly reduced by the cost effective heat-sink approach. In this example, in order to understand and control the self heating effect, a GaN HFET with a flip chip concept is simulated, and device characteristics are compared versus a normal structure.For HFETs, the GaN/AlGaN epitaxial layers have been grown on either sapphire or SiC substrates. Although sapphire has the advantage of lower cost and availabil-ity in larger wafer sizes, its poor thermal conductivity (0.3 W /cm-K) limits the achievable powers due to severe self-heating. The self-heating effect can be significantly reduced by flip-chip mounting the devices onto highly conducting substrates such as AlN (1.8 W /cm-K).The typical GaN HFET flip chip structure in this example is a Al0.25Ga0.75 N-GaN HFET on a sapphire substrate. The structure consists of an AlN layer as a heat sink, a 2.7nm undoped AlGaN layer, and two GaN layers which includes 20nm doped 1e15 GaN and 1um undoped GaN as shown in Figure 31.The self-heating is a local increase of crystal temperature due to dissipated Joule electric power, this effect can sig-nificantly reduce the electron mobility and degrade de -vice performance.DC, Transient and AC simulations are performed and compared with and without the flip chip structure as shown in Figure 32, Figure 33 and Figure 34 respectively. As expected the performance of the device is better us -ing the flip chip architecture.Figure 31. GaN HFET flip chip structure.Figure 32. Drain current versus drain voltage for a FLIP CHIP and normal structure.Figure 33. Drain current versus time for a FLIP CHIP and normal structure.Figure 34. Gain versus frequency for a FLIP CHIP and normal structure.The Simulation StandardPage 10July, August, September 2013Large Signal Output Power AnalysisThis example describes how to simulate typical 10 GHz large-signal measured performance quantities related to power output, such as power out versus power as shown in Figure 35, power gain as shown in Figure 36 and am -plifier efficiency as shown in Figure 37 as the device is over-driven into high distortion. The example also plots in Figure 38 the output signal shape versus time for each of the ten input signal levels simulated.The structure under test is shown in Figure 39.Ten large signal input amplitudes are defined. Each of these waveforms are applied to the gate in order of in-creasing amplitude. After each waveform simulation is complete, a number of large signal parameters are calcu-lated. The peak input and output voltages are extracted, followed by the exact times at which these peak volt -ages occurred. Then the input and output currents are extracted at the same times as the peak voltages occur. It is important to extract the currents at the same time as the peak voltages in order to take account of the phase between current and voltage, so that the correct power values can be calculated.Figure 36. Power gain versus power out.Figure 37. Power Output Efficiency verus Power out.Figure 38. Drain and gate voltage large signal.Figure 39. Structure under test.Figure 35. Power out versus power in.ConclusionGaN is a very promising material for high power switch-ing applications. However, development cost is becom-ing a serious concern for GaN manufacturers. This iswhy TCAD is so important in order to reduce cost andhelp optimize device performance.Silvaco’s Process and Device solutions have all the capa-bilities ( i.e. state of the art mesh, discretization, solversand physcial models) that we think are essential to accu-rately simulate GaN based devices in 2D and 3D.References[1] Naiqian Zhang, “High voltage GaN HEMTs with low on-resitancefor switching applications”, dissertation, UCSB september 2002[2] O.Ambacher et al. “Two-dimensionalelectron gases Induced byspontaneous and piezoelectric polarization charges in N- andGa-face AlGaN/Gan Heterostructures” J. Appl. Phys. Vol 85,3222(1999)[3] Farahmand, M., et al, “Electron Transport Characteristics of GaNfor high temperature device modeling” J. Appl. Phys. Vol 83,4777-4781 (1999)[4] Albrecht, J.D. et al, “Monte Carlo simulation of Electron Transportin the III-Nitride Wurtzite Phase Materials Sustems: binaries andTernaries” IEEE Trans. Electron Device Vol,48, NO. 3 March 2001[5] Ota, K. et. al. “A Normally-off GaN FET with High Threshold Volt-age Uniformity Using A Novel Piezo Neutralization Technique”,IEDM 2009, pp. 153-156.[6] O. Hilt, A. Knauer, F. Brunner, E. Bahat-Treidel and J. W√ºrfl “Nor-mally-off AlGaN/GaN HEFT with p-type GaN Gate and AlGaNBuffer” Ferdinand-Braun-Institut, Leibniz Institut fuer Hoechstfre-quenztechnik Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany.Proceedings of The 22nd International Symposium on Power Semi-conductor Devices & ICs, Hiroshima.[7] Uttam Singisetti, et al., “Enhancement-Mode N -Polar GaN MIS-FETs With Self_Aligned Source/Drain Regrowth” IEEE ElectronDevice Letters. Vol,32, NO. 2 feb 2011.[8] Yasuhiro Uemoto “A Normally-off AlGaN/GaN Transistor withRon=2.6mOhmcm2 and BVds=640V Using Conductivity Modula-tion” published at IEDM 2006.[9] Daniel Balaz from his PhD Thesis from University of Glasgow in2011 entitled “Current collapse and device degradation in AlGaN/GaN heterostructure field effect transistors”.[10] Experimental and simulation study of breakdown voltage enhance-ment of AlGaN/gaN heterostructures by Si substrate removal.D.Visalli et al Apl. Phys. Lett. 97, 113501 2010.July, August, September 2013 Page 11 The Simulation Standard。

The world of chess is a realm of strategy, intellect, and intense competition. It is a game that has been played for centuries, with its roots stretching back to the 6th century in India. Over time, it has evolved into a sophisticated sport that tests the mental fortitude of its players. One of the most exhilarating aspects of chess is the international competitions that bring together the best minds from around the globe.In the heart of a bustling city, the air was thick with anticipation as the international chess tournament commenced. The venue was a grand hall, adorned with the flags of participating nations, each fluttering proudly in the gentle breeze that wafted through the open windows. The atmosphere was electric, abuzz with the chatter of excited spectators, the rustle of anxious players, and the occasional click of a chess piece being moved with calculated precision.The competitors were a diverse group, hailing from different corners of the world. There were seasoned veterans with years of experience, their faces etched with the wisdom of countless games played and won. Young prodigies, brimming with talent and eager to prove themselves, sat alongside them. Each player, regardless of age or experience, shared a common passion for the game that transcended language and culture.The games were a spectacle to behold. The chessboard, a battlefield of 64 squares, was where the real war took place. Each move was a strategic maneuver, a silent conversation between the players. The pieces, the pawns, knights, bishops, rooks, and queens, were the soldiers in this cerebral duel. The king, the ultimate target, was the symbol of victory ordefeat.The players sat hunched over their boards, their faces a mask of concentration. Some would furrow their brows in deep thought, while others would tap their fingers impatiently, waiting for their opponents move. The silence was occasionally broken by the soft thud of a piece being placed on the board, a sound that echoed through the hall, signaling a decisive move.The games were not just a test of skill but also of character. The players had to maintain their composure under pressure, to think several moves ahead, and to adapt to the everchanging dynamics of the game. It was a dance of wits, a silent duel that required patience, foresight, and an unwavering focus.The tournament was a celebration of the human minds capacity for strategic thinking and problemsolving. It showcased the beauty of chess as an art form, a blend of creativity and logic. The players were not just competitors they were artists, each painting their own unique masterpiece on the canvas of the chessboard.As the tournament progressed, the excitement only grew. The initial rounds whittled down the field, with each game bringing the players closer to the coveted title. The crowd watched with bated breath as the tension mounted, the air thick with the scent of victory and the sting of defeat.The final game was a nailbiting affair, a clash of titans that had theaudience on the edge of their seats. The two finalists, both seasoned players with a reputation for their tactical prowess, engaged in a fierce battle of wits. The game was a rollercoaster of emotions, with moments of brilliance and heartstopping blunders.In the end, it was a single move, a masterstroke that sealed the fate of the game. The champion emerged, a look of triumph on their face, while the runnerup graciously accepted their defeat. The applause was deafening, a testament to the respect and admiration the audience had for both players.The international chess tournament was more than just a competition it was a gathering of minds, a celebration of the game that brought people together from all walks of life. It was a testament to the power of chess as a universal language, a game that transcended borders and united people in their shared love for the sport.As the tournament concluded, the players and spectators alike left with a sense of fulfillment and a newfound appreciation for the game. The memories of the games played, the strategies employed, and the friendships forged would linger long after the last piece had been moved. The international chess competition was a reminder of the beauty of the human mind and the endless possibilities it holds when challenged.。

第1章什么是仿真仿真（simulation）是模仿实际系统行为的一类广泛方法和应用手段，通常借助计算机和相应的软件来实现。

事实上，“仿真”一词具有非常宽泛的含义，其思想可应用于各种不同的领域和行业。

目前，随着计算机和软件前所未有的高速发展，仿真变得越来越普及和功能强大。

本书为读者较为全面地阐述了仿真的一般理论，特别讲述了一种专用仿真工具软件Arena的使用。

本书第1章和第2章介绍了仿真的一般思想和逻辑，第3－9章着重讲述Arena 的使用。

然而，我们并不准备把本书作为包罗Arena一切的一本完整的参考手册（Arena的在线帮助系统具有此项功能）。

第10章告诉读者如何把Arena与外部文件及其它应用程序相集成，并对Arena的一些高阶功能进行了总结评述；第11章介绍了如何应用Arena对连续系统和离散/连续混合系统加以建模；第12－13章讨论了有关如何对仿真试验进行计划、如何对结果加以解释、以及如何管理仿真项目等问题。

附录A是一个为《华盛顿邮报》实施的仿真项目的详细记述；附录B给出了近期“Arena建模学生竞赛”中几个相当复杂的问题，该竞赛是由美国工业工程师协会（Institute of Industrial Engineers）与Rockwell软件公司（先前的System Modeling公司）联合举办的；附录C提供了仿真所必须的概率论与数理统计知识的快速复习；附录D描述了Arena用到的各种概率分布；附录E提供了软件的安装指南。

阅读完本书以后，读者应能应用Arena对各种系统进行建模，并能成功且有效地从事仿真研究。

本章讲述了仿真的一般概念。

1.1节提出了一些应如何研究系统模型的一般思路，并给出了几个例子说明仿真在什么情况下有用。

1.2节包含了有关仿真及其普及性的更具体的信息，介绍了仿真的长处（及一项短处），并尝试对人们所作的各种仿真加以分类。

1.3节简要介绍了实现仿真的几种方式。

最后，1.4节追溯了仿真手段和应用场合的发展变化。