Device Processing Studies of Aluminum-Rich AlGaN Superlattices

pi将研究深紫外发光二极管（led）生长和加工中的关键问题。感兴趣的波长范围为280 ~ 240 nm，将使用纳米周期（1.25 ~ 2.25 nm）的AlN/AlxGa1-xN超晶格（SLs）来达到。他们从增长到设备处理的具体目标是：由于AlxGa1-xN的空穴活化能随着x的增加而增加，因此很难获得高的p型载流子浓度。实验将解决在达到高载流子浓度时能隙的优化问题。2. LED的性能取决于与p型和n型材料形成欧姆接触的能力。这些材料的情况由于暴露在空气中形成的天然氧化物的存在而变得复杂。他们建议通过控制生长和金属沉积之间的空气暴露来研究和改善这些富铝表面的接触电阻。3. 生产台面器件结构依赖于等离子体蚀刻。他们的初步工作表明AlN/AlGaN SL腐蚀速率取决于成分和掺杂。此外，他们发现一旦等离子体条件建立，蚀刻的开始会延迟，我们将其归因于天然氧化物的形成。他们将研究这些效应以控制器件结构的蚀刻。蚀刻条件对它们形成欧姆接触能力的影响需要了解。他们提出系统的实验来解决这些重要问题。知识价值。这一基础研究解决了生产深紫外led必须进行的问题。将开发先进的生长方法来控制富氮材料的能量缺口和材料质量。将研究掺杂的意义，并讨论电接触和等离子体刻蚀的加工问题。最终目标是演示在240纳米范围内工作的深紫外LED。高功率led在深紫外范围内的应用扩展到生物、化学和环境传感，从而关系到当前的国家安全问题。更广泛的影响。跨学科的研究环境结合了物理学、材料科学和高级工程学。这为理工科研究生和本科生在这些领域发展重要的技术、团队和领导能力提供了极好的机会。他们将继续参与德州理工学院、地区大学以及当地的外展和招聘活动。这些努力旨在增加大学研究社区中合格学生的数量，使年轻学生对科学和工程职业产生兴趣，并从富有代表性不足的地区学生社区中招募人才。

The PIs will investigate critical issues in growth and processing of deep ultraviolet light emitting diodes (LEDs). The wavelength range of interest is from 280 to 240 nm, and will be reached using AlN/AlxGa1-xN superlattices (SLs) with nanometer periods (1.25 - 2.25 nm). Their specific goals to advance from growth to device processing are: 1. High p-type carrier concentrations are difficult to obtain due to the increasing hole activation energy in AlxGa1-xN with increasing x. Experiments will address the optimization of energy gap while reaching high carrier concentrations. 2. LED performance relies on the ability to form Ohmic contacts to p-type and n-type materials. The situation for these materials is complicated by the presence of native oxides which form upon exposure to air. They propose to study and improve contact resistance for these Al-rich surfaces by controlling air exposure between growth and metal deposition. 3. Producing mesa device structures relies on plasma etching. Their preliminary work shows the AlN/AlGaN SL etch rates to depend on composition and doping. Furthermore, they find a delay in the onset of etching, once plasma conditions are established, which we attribute to native oxide formation. They will study these effects for controlling the etch of device structures. The influence of etching conditions on their ability to form Ohmic contacts needs to be understood. They propose systematic experiments to address these important issues.Intellectual Merit. This fundamental research addresses must be carried out to produce deep UV LEDs. Advanced growth methods will be developed to control energy gaps and material quality in AlN-rich materials. Implications for doping will be studied, and processing issues of electrical contacts and plasma etching addressed. The final goal is to demonstrate a deep UV LED operating in the 240 nm range. The application of high power LEDs in the deep UV range extends to biological, chemical, and environmental sensing, thus relating to current national security issues.Broader Impact. The interdisciplinary research setting combines physics, materials science, and advanced engineering. This provides excellent opportunities in these areas for graduate and undergraduates students from science and engineering, developing important technical, team, and leadership abilities. They will continue their involvement in Texas Tech, regional university, and local outreach and recruitment activities. These efforts strive to increase the number of qualified students in their University research community, interest young students in science and engineering careers, and recruit from the regional community of students rich in underrepresented talent.