Efficiency and droop improvement in InGaN LED by selective carrier distribution manipulation

如何提高理科效率英语作文Improving Efficiency in Science Studies。

Efficiency in learning science is crucial for academic success and a deeper understanding of the subject. Effective study methods not only enhance our comprehension but also optimize our time and efforts. In this essay, we will explore several strategies to boost efficiency in science studies.First and foremost, organization plays a pivotal role in improving efficiency. By maintaining a tidy study environment, students can reduce distractions and focus better on their tasks. It is advisable to keep study materials neatly arranged, including textbooks, notes, and stationery. Digital tools such as apps for note-taking and organizing schedules can also be immensely helpful in this regard.Furthermore, setting clear goals is essential.Establishing specific, achievable objectives for each study session can provide direction and motivation. For instance, one might aim to complete a certain number of practice problems or thoroughly understand a specific concept within a defined timeframe. These goals help structure study sessions and enable students to track their progress effectively.Another effective strategy is active engagement with the material. Passive reading or listening often leads to shallow understanding and limited retention. Instead, students should adopt active learning techniques such as summarizing key points, discussing concepts with peers, or teaching the material to others. These methods not only reinforce understanding but also make learning more enjoyable and memorable.In addition to active learning, regular practice is vital for mastering scientific subjects. Solving problems and applying theoretical knowledge in practical scenarios enhances critical thinking and problem-solving skills. Students should allocate time for regular practice sessionsand seek additional exercises to challenge themselves.Moreover, leveraging technology can significantly enhance efficiency in science studies. Online resources, educational apps, and interactive simulations can provide supplementary explanations and visualizations thatfacilitate understanding. Virtual laboratories and multimedia presentations can make abstract concepts more tangible and accessible.Effective time management is another key aspect of efficient studying. Creating a study schedule andallocating specific time slots for different topics or tasks can prevent procrastination and ensure consistent progress. Additionally, taking breaks at regular intervals can prevent burnout and improve overall productivity.Furthermore, seeking help and clarification when needed is crucial for efficient learning. Students should not hesitate to ask questions in class or consult teachers, peers, or online resources to resolve doubts. Addressing misunderstandings promptly prevents confusion fromescalating and facilitates continuous learning.Lastly, adopting a growth mindset can boost efficiency in science studies. Believing in one's ability to improve through effort and perseverance fosters resilience and a positive attitude towards challenges. Embracing mistakes as opportunities for learning and growth encourages continuous improvement and enhances overall efficiency.In conclusion, efficiency in science studies can be achieved through a combination of effective organization, goal-setting, active engagement, regular practice, technology integration, time management, seeking help when needed, and cultivating a growth mindset. By implementing these strategies consistently, students can optimize their learning experience, deepen their understanding ofscientific concepts, and excel academically in the field of science.。

如何提升效率的英语作文英文回答：Improving efficiency is crucial in any field to optimize performance and achieve desired outcomes. Here are some effective strategies to enhance efficiency:1. Prioritize Tasks:Identify the most important tasks and allocate time accordingly. Use the Eisenhower Matrix or ABCDE Method to categorize tasks based on urgency and importance.2. Time Management:Plan your schedule strategically, allocate specific time slots for different tasks, and stick to them. Usetime-tracking tools to monitor your progress and identify areas for improvement.3. Delegate and Outsource:If possible, delegate tasks to others or outsource non-essential activities to free up your time for higher-priority responsibilities.4. Automation:Leverage technology to automate repetitive and time-consuming tasks. This frees up your time for more value-added activities.5. Streamline Processes:Analyze existing processes and identify bottlenecks or inefficiencies. Implement improvements to reduce waste and streamline operations.6. Enhance Communication:Establish clear communication channels and processes to avoid misunderstandings, delays, and rework.7. Continuous Improvement:Regularly evaluate your efficiency and identify areas for improvement. Seek feedback from colleagues, mentors, or customers to uncover blind spots.8. Eliminate Distractions:Create a distraction-free work environment. Minimize interruptions, minimize social media use, and use noise-canceling headphones if necessary.9. Focus on Outcomes:Keep the end goals in mind and focus on delivering meaningful outcomes rather than getting caught up in unnecessary details.10. Rest and Recovery:Take regular breaks and prioritize self-care tomaintain optimal mental and physical health. This will enhance your productivity and prevent burnout.中文回答：如何提升效率。

prefer如何提升效能,英语作文In today’s fast-paced world, efficiency has become a focal point for achieving success in various aspects of life, including work, education, and personal management. One effective approach to enhancing efficiency is through the identification and cultivation of individual preferences. By aligning tasks with personal inclinations and natural strengths, individuals can not only save time but also boost their overall productivity and satisfaction.Firstly, understanding personal preferences is crucial. Each individual has unique strengths, weaknesses, and areas of interest. By taking the time to analyze what activities resonate most, individuals can better allocate their energy and resources. For instance, someone who thrives in a collaborative environment may be more productive when working in teams rather than in isolation. On the other hand, anintroverted individual might find greater efficiency in tasks that allow for focused concentration. By recognizing these inclinations, one can make more informed choices about the work they take on and the environments they choose to operate in.Furthermore, leveraging technology to manage preferences can significantly enhance efficiency. Various tools and applications are available that help individuals identify their productivity patterns and preferences. For example, time-tracking software can provide insights into when one is most productive during the day and what tasks tend to drain energy. By aligning work schedules with peak productivity hours, individuals can tackle high-priority tasks when they are naturally inclined to perform at their best.In addition to personal analysis, seeking feedback from peers can also play a crucial role in refining one's understanding of preferences. Engaging in discussions andreceiving constructive criticism can reveal blind spots about one’s strengths and weaknesses. For example, in a team setting, colleagues might notice that a certain individual excels in problem-solving or creative brainstorming. Such insights can guide individuals to focus on roles or tasksthat best suit their abilities, ultimately leading to better performance and job satisfaction.Moreover, it is essential to cultivate an environmentthat nurtures these preferences. Organizations that recognize the importance of individual strengths tend to see higher levels of engagement and efficiency among their employees. By providing opportunities for individuals to work on projects that align with their interests, companies can foster a culture of motivation and creativity. This not only benefits the individuals but also propels the entire organization toward greater success.Lastly, developing a sense of self-awareness andflexibility is vital for effective efficiency enhancement. Preferences can change over time due to various factors, including personal growth, changes in work environment, or the acquisition of new skills. Regularly revisiting one’s preferences and being open to adaptation allows for continuous improvement in productivity strategies.In conclusion, enhancing efficiency through preferencesis an achievable goal that requires self-analysis, feedback, effective use of technology, and a supportive environment. By understanding and utilizing personal strengths, individuals can maximize their productivity and find greater satisfaction in their tasks, leading to both personal and professional success. Through a dedicated approach to recognizing and aligning with our preferences, we can all work smarter, not harder.。

英语作文-如何提升教育培训服务行业的服务效率和效果In the realm of education and training services, efficiency and effectiveness are paramount. The industry is tasked with the noble goal of enlightening minds and equipping individuals with the skills necessary for success. To elevate the service efficiency and outcomes in this sector, a multifaceted approach is required, one that harnesses the power of technology, pedagogy, and personalized learning experiences.Technology Integration。

The digital revolution has provided us with tools that can transform the educational landscape. By integrating Learning Management Systems (LMS), educators can streamline course administration and deliver content more effectively. These platforms also offer valuable data analytics, enabling instructors to track progress and tailor interventions to student needs.Active Learning Techniques。

如何提升效率的英语作文英文回答：How to Enhance Efficiency: A Comprehensive Guide.Introduction.In today's fast-paced world, efficiency is paramount to personal and professional success. However, manyindividuals struggle to maximize their productivity and achieve their desired outcomes. This comprehensive guide will provide practical strategies and actionable tips to help you enhance your efficiency and unlock your full potential.1. Establish Clear Goals and Priorities.Define your objectives and prioritize tasks based on importance and urgency.Utilize tools such as to-do lists, task managers, and goal-setting frameworks to keep track of your progress.Break down large projects into manageable chunks to avoid feeling overwhelmed.2. Optimize Time Management.Implement time-management techniques such as the Pomodoro Technique or the Eisenhower Matrix.Delegate tasks whenever possible to free up your time for more critical work.Utilize technology to automate repetitive tasks and schedule appointments efficiently.3. Create a Productive Workspace.Design an organized and clutter-free workspace to minimize distractions and enhance focus.Ensure your workspace has adequate lighting, ventilation, and ergonomic seating.Consider using noise-canceling headphones or white noise to create a conducive environment for concentration.4. Cultivate Effective Work Habits.Establish a consistent work schedule and stick to it as closely as possible.Take regular breaks to prevent burnout and maintain focus.Practice mindfulness and engage in activities that promote mental clarity and well-being.5. Leverage Technology.Explore productivity apps and software that can streamline your workflow and automate tasks.Utilize communication and collaboration tools to facilitate effective teamwork and reduce email overload.Consider using project management tools to track progress and ensure accountability.6. Communicate Effectively.Set clear expectations with colleagues and supervisors to avoid misunderstandings and delays.Provide regular updates and feedback to keep everyone informed.Utilize communication tools effectively to convey information concisely and efficiently.7. Continuous Improvement.Regularly evaluate your efficiency and identify areas for improvement.Seek feedback from colleagues or mentors to gain valuable insights and perspectives.Experiment with different strategies and techniques to optimize your productivity.Conclusion.Enhancing efficiency is a continuous journey that requires conscious effort and ongoing improvement. By implementing the strategies outlined in this guide, you can streamline your workflow, maximize your productivity, and achieve your goals with greater ease and effectiveness. Remember, efficiency is not simply about doing more; it is about doing the right things, in the right way, and at the right time. Embrace these principles and unlock the path to a more efficient, fulfilling, and successful life.中文回答：如何提高效率，一份全面指南。

英语作文-提高工作效率的10个方法Improving Work Efficiency: 10 Methods to Enhance Productivity。

In today's fast-paced world, where time is of the essence, improving work efficiency is paramount for success. Whether you're a student, professional, or entrepreneur, mastering the art of productivity can significantly impact your outcomes. Here are ten effective methods to boost your productivity and achieve your goals more efficiently:1. Set Clear Goals: Begin by defining clear and achievable goals. Having a clear direction provides focus and motivation. Break down larger goals into smaller, manageable tasks to prevent feeling overwhelmed and maintain momentum.2. Prioritize Tasks: Not all tasks are created equal. Use techniques like the Eisenhower Matrix to distinguish between urgent and important tasks. Focus on high-priority items that align with your goals, and delegate or eliminate tasks that don't contribute to your objectives.3. Time Blocking: Allocate specific time blocks for different tasks or activities. This technique helps minimize distractions and ensures dedicated focus on each task. Avoid multitasking, as it can reduce efficiency and quality of work.4. Utilize Technology: Leverage productivity tools and apps to streamline workflows and automate repetitive tasks. Calendar apps, project management software, and note-taking tools can help organize tasks, set reminders, and collaborate with team members more effectively.5. Limit Distractions: Identify and eliminate potential distractions in your work environment. This could mean turning off notifications, setting boundaries with colleagues, or finding a quiet workspace. Practice mindful work habits to stay focused and productive.6. Take Regular Breaks: Avoid burnout by incorporating regular breaks into your workday. Short breaks can help refresh your mind, improve concentration, and preventdecision fatigue. Use techniques like the Pomodoro Technique to work in focused intervals with short breaks in between.7. Optimize Workspace: Create an ergonomic and clutter-free workspace that promotes productivity. Organize your physical and digital space for easy access to tools and resources. Personalize your environment to inspire creativity and motivation.8. Continuous Learning: Invest in personal and professional development to enhance your skills and knowledge. Stay updated on industry trends, best practices, and emerging technologies. Continuous learning fosters adaptability and innovation, key drivers of productivity.9. Effective Communication: Improve communication skills to streamline collaboration and minimize misunderstandings. Clearly communicate expectations, provide constructive feedback, and actively listen to colleagues. Use communication tools wisely to facilitate efficient information sharing.10. Practice Self-Care: Prioritize self-care to maintain physical, mental, and emotional well-being. Eat nutritious meals, exercise regularly, and get enough sleep to sustain energy levels and cognitive function. Incorporate stress-reduction techniques like meditation or mindfulness to manage workload and maintain balance.By implementing these ten methods, you can enhance your work efficiency, maximize productivity, and achieve greater success in your endeavors. Remember that productivity is not just about doing more tasks but about doing the right tasks effectively. Cultivate habits that support your goals and adapt strategies to suit your individual needs and preferences. With dedication and consistent effort, you can optimize your performance and excel in your endeavors.。

提升效率的英语作文英文回答：Improving Efficiency to Enhance Productivity.In today's fast-paced and competitive business environment, it is imperative for organizations to continuously improve efficiency to enhance productivity and stay ahead of the curve. Enhancing efficiency involves streamlining processes, eliminating waste, and implementing innovative solutions to optimize resource utilization and maximize output.Process Optimization:Analyze existing processes and identify bottlenecks and inefficiencies.Implement automation tools to reduce manual tasks and minimize errors.Establish clear workflows and communication channels to ensure smooth collaboration.Train employees on efficient work practices and provide ongoing support.Waste Elimination:Identify sources of waste, such as unnecessary meetings, excessive paperwork, and redundant tasks.Implement lean principles to eliminate non-value-added activities.Encourage employees to actively seek out opportunities to reduce waste and improve efficiency.Innovative Solutions:Embrace new technologies and explore disruptive solutions that can transform processes.Consider cloud computing, analytics, and collaboration tools to enhance efficiency and productivity.Foster a culture of innovation and encourage employees to contribute ideas for improvement.Measurement and Accountability:Establish clear metrics to track efficiency and productivity improvements.Regularly monitor progress and make adjustments as needed to ensure continuous improvement.Assign accountability to individuals or teams for specific efficiency initiatives.Benefits of Enhanced Efficiency.By effectively implementing efficiency enhancements, organizations can reap numerous benefits, including:Increased productivity and output.Reduced costs and expenses.Improved customer satisfaction.Enhanced competitive advantage.Increased profitability.中文回答：提升效率以提高工作效率。

提高效率的有效方法英语作文English Answer:In today's fast-paced world, finding ways to improve efficiency is more important than ever before. By streamlining processes, eliminating distractions, and harnessing technology, individuals can maximizeproductivity and achieve their goals.One effective method for enhancing efficiency is to establish clear priorities. Prioritizing tasks based on their importance and urgency allows individuals to focus on those that will yield the greatest results. By creating a to-do list or using a task management app, individuals can ensure that they are working on high-value tasks that will contribute to their objectives. Additionally, setting realistic deadlines for each task helps maintain momentum and prevents procrastination.Another key strategy is to optimize one's workspace. Awell-organized and clutter-free environment cansignificantly improve focus and productivity. Clear desk space, ergonomic chairs, and adequate lighting can create a conducive environment for work. Regular breaks throughout the day can also help maintain concentration and prevent burnout.Technology can be a powerful tool for improving efficiency. Utilizing automation tools, cloud-based applications, and project management software can streamline tasks, enhance collaboration, and save time. By leveraging technology, individuals can automate repetitive tasks, share documents and ideas seamlessly, and track progress effectively.In addition to these techniques, it is essential to manage distractions effectively. Identifying andeliminating distractions such as social media, excessive email checking, or unnecessary interruptions can significantly improve focus. Using noise-canceling headphones, setting aside specific time slots for email and social media, and delegating tasks to others can helpminimize distractions and maintain a productive flow.Furthermore, it is crucial to evaluate and adjust processes on a regular basis. By analyzing workflows, identifying bottlenecks, and seeking feedback, individuals can continuously improve efficiency. Open communication with colleagues and supervisors, as well as a willingness to adapt and refine processes, are key to optimizing productivity.中文回答：提升效率的有效方法。

0　引　言AlGaN(Aluminum Gallium Nitride)基深紫外LED(Light Emitting Diode)具有安全环保㊁体积小㊁寿命长㊁节能等诸多优势,在杀菌消毒㊁生物医学检测㊁紫外线固化㊁工业光催化及照明等领域具有广阔的应用前景[1⁃3]㊂但目前AlGaN 基深紫外LED 的发光效率较低,外量子效率大多在10%以下[4]㊂而限制AlGaN 基深紫外LED 发光效率的主要原因之一是高Al 组分AlGaN 材料的P 型掺杂困难,使深紫外LED 器件的空穴注入效率较低㊁串联电阻较大[5⁃7]㊂已有研究表明,相比于目前广泛应用的金属极性AlGaN 材料,氮极性AlGaN 材料在深紫外LED 制备方面具有潜力[8⁃9]㊂由于氮极性与金属极性AlGaN 基LED 中极化电场的方向相反,从而有利于提升载流子向量子阱有源区的注入并增强有源区对载流子的限制[10]㊂同时,在Al 组分渐变增加(从0~0.3)的氮极性AlGaN 薄膜中可实现高浓度的三维空穴气,空穴浓度达1×1018cm -3[11]㊂三维空穴气的形成使组分渐变AlGaN 层的价带拉平㊁导带提升,不仅有利于LED 器件空穴的传输,还有助于抑制LED 器件电子的泄漏[11]㊂Zhao 等[12]研究结果表明,在氮极性AlGaN 基深紫外LED(~279nm)结构中引入组分渐变p ⁃Al x Ga 1-x N(x =0.65~0.75)作为空穴提供层兼电子阻挡层,可有效提高空穴注入效率㊁增加LED 器件峰值发光效率并显著缓解LED 器件在大电流下的效率下降(Efficiency droop)现象㊂为进一步改善氮极性AlGaN 基深紫外LED 的光电特性,笔者在前期氮极性组分渐变AlGaN 基深紫外LED 结构基础上,引入了n +⁃GaN /AlGaN /p +⁃GaN 隧道结结构㊂利用半导体器件模拟软件APSYS 对该隧道结LED 进行了光电特性的模拟仿真研究㊂半导体器件模拟软件是器件物理研究的工具,具有效率高㊁节省资金的特点,并对发现新的物理现象及器件设计具有重要作用㊂因此,将半导体器件模拟相关知识融入到 半导体器件物理”课程中,能有效提升学生对半导体器件物理知识的理解和探索㊂1　器件结构和仿真模型图1为APSYS 模拟仿真中所构建的氮极性AlGaN 基深紫外LED(~272nm)器件的结构示意图㊂其中图1a 为无隧道结参考LED 器件的结构示意图,称该器件为LED⁃A㊂其件结构由3μm 硅掺杂浓度为5×1018cm -3的n ⁃Al 0.65Ga 0.35N㊁5对Al 0.65Ga 0.35N(12nm)/Al 0.5Ga 0.5N(2nm)多量子阱(MQW:Multiple Quantum Well)有源区㊁100nm 沿生长方向Al 组分由0.65向0.75渐变的p ⁃Al x Ga 1-x N(Graded p ⁃Al x Ga 1-x N)和20nm 重掺的p +⁃GaN 欧姆接触层组成㊂LED⁃A 各层结构位于蓝宝石衬底(Sapphire substrate)上,其正㊁负电极分别设置在p +⁃GaN 和n ⁃Al 0.65Ga 0.35N 表面,其横向尺寸均为25μm㊂隧道结LED 器件的结构如图1b 所示㊂图1　模拟仿真中构建的有/无隧道结AlGaN 基深紫外LED 器件的结构示意图Fig.1　Schematic diagrams of the structure of the AlGaN⁃based deep ultraviolet LED　device with /without tunnel junction constructed in the simulation 其在参考LED⁃A 的基础上引入了n +⁃GaN(50nm)/Al 0.4Ga 0.6N (4nm)/p +⁃GaN(50nm)隧道结结构,n +⁃GaN 中硅的掺杂浓度和p +⁃GaN 中镁的掺杂浓度分别为1×1020cm -3和4×1020cm -3㊂称该隧道结LED 为LED⁃B㊂除隧道结外,LED⁃B 的其余结构及材料参数与LED⁃A 相同㊂867吉林大学学报(信息科学版)第41卷模拟实验中,肖克莱⁃瑞德⁃霍尔(SRH:Shockley⁃Read⁃Hall)复合寿命和俄歇复合系数分别设置为10ns 和1×10-30cm 6/s [13⁃14],背景吸收系数和光提取效率分别设置为2000m -1和10%[15⁃16]㊂Al x 1Ga 1-x 1N /Al x 2Ga 1-x 2N 异质结的导带带阶(ΔE c )和价带带阶(ΔE v )之比ΔE c /ΔE v 设置为0.65/0.35㊂考虑缺陷导致的极化电荷屏蔽效应,LED 各层材料的极化因子设置为-0.4[17⁃18],负号表示各层材料的极性均为氮极性㊂实验中应用的其他材料参数见文献[19]㊂APSYS 模拟软件中涵盖了全面的材料和器件物理模型,其基于这些模型能进行泊松方程和载流子连续性方程等物理方程的求解计算,从而得到模拟器件的光电特性㊂2　模拟结果与分析图2为120A /cm 2电流密度下LED⁃A 和LED⁃B 在整个有源区内的电子浓度分布图,其中x 轴代表横向距离,y 轴代表纵向距离㊂图2中通过不同的颜色代表不同位置处电子浓度的对数,即log[电子浓度],电子浓度单位为cm -3㊂从图2可看出,LED⁃A 和LED⁃B 量子阱中的电子浓度峰值差异较小,均在1×1019cm -3附近㊂此外,LED⁃A 量子阱中的电子在x 轴0~50μm 范围内具有较高浓度,而在x 轴50~200μm 范围内电子浓度快速降低,表明LED⁃A 中的电子主要集中在正电极下方的量子阱中㊂对LED⁃B,可明显看到量子阱中电子浓度沿横向分布浓度差异较小,即LED⁃B 中的电子不仅从正电极区域下方注入量子阱,还能沿横向扩展注入量子阱有源区中,使电子在量子阱中的横向分布更为均匀㊂图2　120A /cm 2电流密度下LED 器件量子阱有源区中的电子浓度分布Fig.2　Electron concentration distribution in the active region of quantum wells ofLED devices at a current density of 120A /cm 2同时,模拟得到了120A /cm 2电流密度下空穴在LED⁃A 和LED⁃B 中量子阱有源区内的浓度分布情况,如图3所示㊂图3　120A /cm 2电流密度下LED 器件量子阱有源区中的空穴浓度分布Fig.3　Hole concentration distribution in the active region of quantum wells of LED devices at a current density of 120A /cm 2从图3可看出,空穴浓度在LED⁃A 和LED⁃B 中量子阱横向的分布均匀性结果与电子浓度的分布结果相近㊂根据模拟结果,取点发现LED⁃A 量子阱内的空穴浓度峰值为7.2×1018cm -3,而LED⁃B 量子967第5期张源涛,等:氮极性AlGaN 基隧道结深紫外LED阱内的空穴浓度峰值为4.4×1018cm -3,低于LED⁃A 的空穴浓度峰值㊂尽管LED⁃B 的空穴浓度峰值仅为LED 器件A 的60%,但采用隧道结结构的LED⁃B 在沿x 轴方向上的空穴浓度分布更加均匀㊂从图3还可看出,LED⁃A 仅在x 轴0~50μm 范围内具有较高的空穴浓度,而结构B 在沿x 轴方向上始终维持着较高的空穴浓度,说明LED⁃B 在整个有源区内部具有更高的空穴浓度,可为有源区的辐射复合过程提供更多的空穴㊂载流子浓度在量子阱中横向的分布情况能直接决定量子阱中电子⁃空穴对辐射复合率的横向分布情况㊂图4为120A /cm 2电流密度下LED⁃A 和LED⁃B 中量子阱有源区内电子⁃空穴对辐射复合率的分布图㊂根据模拟结果,得到LED⁃A 的辐射复合率峰值为1.19×1027cm -3㊃s -1,而LED⁃B 的辐射复合率峰值为5.2×1026cm -3㊃s -1,约为LED⁃A 的1/2㊂然而,LED⁃A 的辐射复合仅局限在正电极下方0~50μm 区域内的量子阱中,而LED⁃B 在器件量子阱的整个横向区域内(0~200μm)均存在较高的辐射复合率㊂这是因为LED⁃B 在量子阱整个横向区域具有较高浓度㊁较为均匀的电子和空穴分布,如图2和图3所示㊂因此,在深紫外LED 器件中引入隧道结结构可以避免载流子在电极下方集中注入量子阱有源区,有利于改善LED 的发光均匀性㊂需要注意的是,LED⁃A 的电流主要在正电极下方集中注入,这会引起正电极下方量子阱区域积累高浓度的电子和空穴,过高浓度的空穴会增加俄歇复合率,不利于器件发光效率的提升㊂图4　120A /cm 2电流密度下LED 器件量子阱有源区中辐射复合率分布Fig.4　Radiative recombination rate distribution in the active region of quantumwells of LED devices at a current density of 120A /cm 2图5a 和图5b 分别为LED⁃A 和LED⁃B 的内量子效率和光输出功率曲线㊂从图5中可看出,具有隧道结结构的LED⁃B 的峰值内量子效率为61.3%,明显高于无隧道结结构LED⁃A 的55.8%㊂另外,LED⁃A 的内量子效率随电流密度增加下降的更明显,其在600A /cm 2注入电流密度下的内量子效率为49.1%,内量子效率相比峰值效率下降了12.0%㊂而LED⁃B 在600A /cm 2注入电流密度下的内量子效率为58.6%,内量子效率相比峰值效率仅下降4.4%,约为LED⁃A 效率下降量的1/3㊂为此,通过APSYS 软件中所采用的内量子效率ηIQE 的计算公式ηIQE =I rad I rad +I nonrad =Bn 2An +Bn 2+Cn 3,(1)对其进行研究,其中n 为电子浓度,I rad =Bn 2为辐射复合率,B 为辐射复合率系数;I nonrad =An +Cn 3为非辐射复合率,其中An 为SRH 复合率,A 为SRH 复合系数,Cn 3为俄歇复合率,C 为俄歇复合系数㊂通过式(1)可看出,俄歇复合率与载流子浓度的3次方成正比,其受载流子浓度变化的影响较大㊂LED⁃A 正电极下方量子阱中较高浓度载流子的积聚会大幅增加俄歇复合率,使内量子效率偏低,尤其是在大电流密度下将产生较严重的内量子效率下降现象㊂对LED⁃B,其更强的电流扩展能力,使量子阱平面内的载流子浓度不易过高且更为均匀,可有效降低俄歇复合率,提升器件的内量子效率,并缓解器件在大电流密度下的效率下降㊂此外,从图5a 的光输出功率密度曲线也可看出,LED⁃B 的光输出功率密度大于LED⁃A,且其输出功率的差值随电流密度的增加而逐渐增大,表明LED⁃B 具有更好的发光特性㊂077吉林大学学报(信息科学版)第41卷图5　LED⁃A 和LED⁃B 的内量子效率㊁光输出功率和I⁃V 特性曲线Fig.5　Internal quantum efficiency ,light output power ,and I⁃V curves of LED⁃A and LED⁃B 图5c 为LED⁃A 和LED⁃B 的电流⁃电压特性曲线㊂可以看出LED⁃B 具有更低的开启电压(~6V),约为LED⁃A 开启电压(~12V)的一半㊂并且LED⁃B 的电流值随电压的增大而快速增加,说明LED⁃B 具有更低的串联电阻㊂假定器件尺寸均为200×200μm 2,则根据I⁃V 特性曲线斜率计算出LED⁃A 和LED⁃B 的串联电阻分别为166Ω和71Ω㊂LED⁃B 更低的串联电阻可有效降低器件工作时的产热量,同时也有利于提高器件的功率效率㊂以上结果表明,隧道结的引入不仅提升了氮极性AlGaN 基深紫外LED 的发光效率,还有效降低了器件的开启电压㊂3　结　语笔者采用半导体器件模拟软件APSYS,研究了带有n +⁃GaN /Al 0.4Ga 0.6N /p +⁃GaN 隧道结结构的氮极性AlGaN 基深紫外LED 的光电特性㊂研究结果表明,与无隧道结结构的参考LED 相比,隧道结LED 的电流扩展能力大大增强,有效避免了电子和空穴在正电极下方量子阱中的集中积聚,提高了载流子在量子阱平面内较为均匀的分布,降低了俄歇复合率,提升了器件的发光效率和开启电压㊂该研究结果对高性能氮化物深紫外LED 器件的制备具有指导意义㊂半导体器件模拟软件是器件物理研究的工具,具有高效率㊁节省资金的特点,并对发现新的物理现象及器件设计具有重要作用㊂如果学生在学习 半导体器件物理”课程的同时,加强对半导体器件模拟仿真的学习,将有助于对课程内容的深入掌握㊂参考文献:[1]YANG J,ZHAO D G,LIU Z S,et al.A 357.9nm GaN /AlGaN Multiple Quantum Well Ultraviolet Laser Diode [J].Journalof Semiconductors,2022,43(1):010501.[2]JIANG K,SUN X J,ZHANG Z H,et al.Polarization⁃Enhanced AlGaN Solar⁃Blind Ultraviolet Detectors [J].PhotonicsResearch,2020,8(7):1243⁃1252.[3]YU H B,MEMON M H,WANG D H,et al.AlGaN⁃Based Deep Ultraviolet Micro⁃LED Emitting at 275nm [J].OpticsLetters,2021,46(13):3271⁃3274.[4]LIANG S H,SUN W H.Recent Advances in Packaging Technologies of AlGaN⁃Based Deep Ultraviolet Light⁃Emitting Diodes[J].Advanced Materials Technologies,2022,7(8):210502⁃210519.[5]REN Z J,YU H B,LIU Z L,et al.Band Engineering of Ⅲ⁃Nitride⁃Based Deep⁃Ultraviolet Light⁃Emitting Diodes:A Review[J].Journal of Physics D:Applied Physics,2020,53(7):073002.[6]CHU C S,TIAN K K,CHE J M,et al.On the Impact of Electron Leakage on the Efficiency Droop for AlGaN Based DeepUltraviolet Light Emitting Diodes [J].IEEE Photonics Journal,2020,13(3):1600207.[7]LIANG Y H,TOWE E.Progress in Efficient Doping of High Aluminum⁃Containing Group III⁃Nitrides [J].Applied PhysicsReviews,2018,5(1):011107.[8]ZHUANG Z,ILDA D,OHKAWA K.Enhanced Performance of N⁃Polar AlGaN⁃Based Deep⁃Ultraviolet Light⁃Emitting Diodes[J].Optics Express,2020,28(21):30423⁃30431.[9]GUO W,SUN H D,TORRE B,et teral⁃Polarity Structure of AlGaN Quantum Wells:A Promising Approach to Enhancing the Ultraviolet Luminescence [J].Advanced Functional Materials,2018,28(32):1802395.177第5期张源涛,等:氮极性AlGaN 基隧道结深紫外LED277吉林大学学报(信息科学版)第41卷[10]AKYOL F,NATH D N,KEISHNAMOORTHY S,et al.Suppression of Electron Overflow and Efficiency Droop in N⁃Polar GaN Green Light Emitting Diodes[J].Applied Physics Letters,2012,100(11):111118⁃1⁃111118⁃4.[11]YAN L,ZHANG Y,HAN X,et al.Polarization⁃Induced Hole Doping in N⁃PolarⅢ⁃Nitride LED Grown by Metalorganic Chemical Vapor Deposition[J].Applied Physics Letters,2018,112(18):182104⁃1⁃182104⁃4.[12]ZHAO Y B,DENG G Q,NIU Y F,et al.Performance Enhancement of an N⁃Polar Nitride Deep⁃Ultraviolet Light⁃Emitting Diode with Compositionally Graded p⁃AlGaN[J].Optics Letters,2022,47(2):385⁃388.[13]CHEN F M,HUANG M F,CHANG J Y,et al.Effects of Number of Quantum Wells and Shockley⁃Read⁃Hall Recombination in Deep⁃Ultraviolet Light⁃Emitting Diodes[J].Optics Letters,2020,45(13):3749⁃3752.[14]KANG Y,YU H B,REN Z J,et al.Efficiency Droop Suppression and Light Output Power Enhancement of Deep Ultraviolet Light⁃Emitting Diode by Incorporating Inverted⁃V⁃Shaped Quantum Barriers[J].IEEE Transactions on Electron Devices, 2020,67(11):4958⁃4962.[15]LIU N N,GU H M,WEI Y,et al.Performance Enhancement of AlGaN⁃Based Deep Ultraviolet Light⁃Emitting Diodes by Using Stepped and Super⁃Lattice N⁃Type Confinement Layer[J].Superlattice Microstructures,2020,141:1⁃6.[16]VELPULA R T,JAIN B,BUI H T,et al.Improving Carrier Transport in AlGaN Deep⁃Ultraviolet Light⁃Emitting Diodes Usinga Strip⁃in⁃a⁃Barrier Structure[J].Applied Optics,2020,59(17):5276⁃5281.[17]HUANG P Y,XIAO L F,CHEN X F,et al.Efficiency Improvement of AlGaN⁃Based Deep Ultraviolet LEDs with Gradual Al⁃Vomposition AlGaN Conduction Layer[J].Optoelectronic Letters,2020,16(4):279⁃283.[18]KUO Y K,CHEN F M,CHANG J Y,et al.Design and Optimization of Electron⁃Blocking Layer in Deep Ultraviolet Light⁃Emitting Diodes[J].IEEE Journal of Quantum Electronics,2020,56(1):1⁃6.[19]VURGAFTMAN I,MEYER J R.Band Parameters for Nitrogen⁃Containing Semiconductors[J].Journal of Applied Physics, 2003,94(6):3675⁃3696.(责任编辑:张洁)第41卷　第5期吉林大学学报(信息科学版)Vol.41　No.52023年9月Journal of Jilin University (Information Science Edition)Sept.2023文章编号:1671⁃5896(2023)05⁃0773⁃07基于CST 的电磁脉冲效应分析仿真实验研究收稿日期:2022⁃11⁃02基金项目:吉林省教育厅科学技术研究基金资助项目(JJKH20231171KJ)作者简介:霍佳雨(1980 ),女,长春人,吉林大学高级工程师,博士,主要从事光电子技术研究,(Tel)86⁃131****2310(E⁃mail)huojy@㊂霍佳雨,高　博,史竟文(吉林大学通信工程学院,长春130012)摘要:为减小复杂多变的电磁环境对车辆的影响,利用三维电磁场仿真软件CST (Computer Simulation Technology)在车辆发动机舱建立线缆模型,研究不同因素对车辆电磁耦合效应的影响㊂通过仿真得到线缆长度㊁线缆距车底高度㊁线缆相对距离㊁线缆终端电阻㊁导体半径㊁绝缘层厚度等参数变化下,线缆感应电压和感应电流的峰值绘制关系曲线㊂这些结论可以为车辆线束设计提供理论指导,并为电磁防护设计中对于线缆导体半径选择㊁线缆相对距离㊁离地高度㊁线缆长度等提供依据㊂关键词:电磁脉冲;三维电磁场仿真软件CST;电磁防护;车辆线束;电磁辐射敏感度中图分类号:TN973.3文献标志码:AResearch on Simulation Experiment of Electromagnetic Pulse Effect Analysis Based on CSTHUO Jiayu,GAO Bo,SHI Jingwen(College of Communication Engineering,Jilin University,Changchun 130012,China)Abstract :To reduce the influence of complex and changeable electromagnetic environment on vehicles,the cable model is built in the engine compartment by using the three⁃dimensional electromagnetic field simulation software CST(Computer Simulation Technology)to study the influence of different factors on the electromagnetic coupling effect of vehicles.Through simulation,the peak relationship curves between induced voltage and induced current in the cable are drawn when the parameters such as cable length,cable height from the bottom of the car,cable relative distance,cable terminal resistance,conductor radius,and insulation layer thickness change.These conclusions can provide theoretical guidance for the design of vehicle wire harnesses,and provide a basis for the conductor radius selection,cable relative distance,height from the ground,and cable length in electromagnetic protection design.Key words :electromagnetic pulse;computer simulation technology(CST);electromagnetic protection;vehicle harness;electromagnetic radiation susceptibility 0　引　言随着微电子技术的飞速发展,现代车辆使用的电子设备越来越多㊂集成电路的复杂化㊁小型化,导致车辆电控系统电磁敏感性不断提升[1⁃2]㊂大功率电磁脉冲不仅会对车辆的电子设备造成直接伤害,还会通过天线㊁线束或孔径进行强耦合,对车内设备造成间接损坏[3⁃4]㊂线束是连接车内各种电子设备的纽带,也是车辆系统引入电磁脉冲威胁的关键性耦合途径㊂以车辆线束为对象,研究其可能遭遇的强电磁脉冲威胁㊁防护加固思路以及具体措施,提升车辆在强电磁脉冲环境中的生存能力成为当前国内外。

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