Device Processing Studies of Aluminum-Rich AlGaN Superlattices

PIS将调查深紫外光发光二极管(LED)的生长和加工中的关键问题。感兴趣的波长范围从280到240 nm，并将达到使用纳米周期(1.25-2.25 nm)的AlN/AlxGa1-xN超晶格(SLS)。他们从生长到器件加工的具体目标是：1.由于AlxGa1-xN中的空穴激活能随着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的同时优化能隙的问题。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。这些材料的情况因暴露在空气中而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.台面器件结构的制作依赖于等离子体刻蚀。他们的初步工作表明，AlN/AlGaN SL的刻蚀速率取决于成分和掺杂。此外，他们发现，一旦建立了等离子体条件，刻蚀的开始就会延迟，我们将其归因于自然氧化物的形成。他们将研究这些效应，以控制器件结构的刻蚀。需要了解刻蚀条件对它们形成欧姆接触能力的影响。他们提出了系统的实验来解决这些重要的问题。这项基础性研究解决了生产深紫外光LED必须进行的问题。将开发先进的生长方法来控制富AlN材料的能隙和材料质量。将研究掺杂的影响，并解决电接触和等离子刻蚀的加工问题。最终目标是展示一种工作在240 nm范围内的深紫外光LED。大功率LED在深紫外区的应用扩展到生物、化学和环境传感，从而涉及到当前的国家安全问题。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提供了极好的机会，培养他们重要的技术、团队和领导能力。他们将继续参与德克萨斯理工大学、地区大学以及当地的外展和招聘活动。这些努力致力于增加大学研究界的合格学生数量，吸引年轻学生对科学和工程职业感兴趣，并从地区社区招聘人才不足的学生。

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.