Advanced doping techniques for AlGaN-based power devices

非技术性：电力半导体设备对能源基础设施至关重要。到2030年，高达80%的发电量将在使用前至少经过一个电力转换阶段。因此，最大限度地提高执行电力转换的设备的能效是至关重要的。基于第三族元素氮化物的电力开关将成为未来电网的基石。虽然基于III-氮化物的功率二极管已经开发出来，但下一代功率二极管和开关的研究还需要启动。下一代可能的候选材料是超宽带隙氮化铝(AlN)和富铝氮化镓(AlGaN)。该项目将为通过掺杂剂工程控制III-氮化物的电子性质奠定基础。这为基于基本半导体工艺的器件设计提供了强大的工具箱，但了解到工艺需要针对目标应用进行定制。掺杂的进步将带来可靠的器件，能够切换前所未有的功率密度，并在超出传统限制的温度下运行。该项目的最终影响将是通过允许有效利用和传输电能来保护和扩大自然资源。该项目还可以开发紫外线LED和激光器。技术：拟议的研究将在n型富铝AlGaN中建立先进的掺杂能力，以实现掺杂工具箱，作为实现新型功率肖特基二极管或HEMT器件结构的第一步。该计划基于这样的假设，即AlGaN甚至潜在的AlN可以与技术上相关的自由载流子浓度n掺杂，以实现这种功率开关所期望的电势。基于这一假设，最终的技术目标是在AlGaN中实现可控的n型掺杂，从而实现一个实用的掺杂工具箱，从而实现先进的功率器件结构。需要解决以下挑战：(1)通过控制补偿器的本底浓度将AlGaN掺杂到低掺杂范围(10E16/cm^3)的漂移层应用中，(2)通过识别和控制自补偿来控制高掺杂范围(1E19/cm^3)的自由电子浓度，以及(3)通过应用离子注入和准缺陷费米能级控制等非平衡过程来抑制DX中心的形成。此外，通过使用替代掺杂剂，如Ge，可以实现更宽的掺杂范围和更好的补偿控制。我们的团队不仅展示了新颖的点缺陷控制方案，而且还展示了其能力，如基于AlGaN的肖特基二极管和深紫外光激光器，走在了这些发展的前沿。这项拟议的研究将开发一个独特的框架，通过该框架在超宽带隙半导体和相关电子材料中实现掺杂工程的概念。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical:Power semiconductor devices are critical for the energy infrastructure. By 2030, as much as 80% of generated electricity will pass through at least one power conversion stage before use. Maximizing the energy efficiency of devices that perform power conversion is therefore of utmost importance. Power switches based on nitrides of Group III elements will be the building blocks of future power grids. While power diodes based on III-nitrides have been developed, research for the next generation of power diodes and switches needs to be initiated. A potential material candidate for the next generation is the ultrawide bandgap aluminum nitride (AlN) and Al-rich aluminum gallium nitride (AlGaN). This project will establish the fundamentals for controlling the electronic properties of III-nitrides by dopant engineering. This provides a robust toolbox for the design of devices based on basic semiconductor processing, but with the understanding that processes need to be tailored to the targeted applications. Doping advances will lead to reliable devices capable of switching unprecedented power densities and operating at temperatures beyond traditional limits. The ultimate impact of this project will be to preserve and extend natural resources by allowing for the efficient use and transmission of electrical energy. This project could also enable the development of ultraviolet LEDs and lasers.Technical:The proposed study will establish advanced doping capabilities in n-type Al-rich AlGaN to realize a doping toolbox as the first step towards the realization of a novel power Schottky diode or HEMT device structure. The program is based on the hypothesis that AlGaN and potentially even AlN can be n-doped with technologically relevant free carrier concentrations to realize the potential expected from such power switches. Based on this hypothesis, the ultimate technical goal is to demonstrate controllable n-type doping in AlGaN, thus realizing a practical doping toolbox to allow for the realization of advanced power device structures. The following challenges need to be met: (1) doping of AlGaN with Si in the low doping range (10E16/cm^3) for drift layer applications by controlling the compensator background concentration, (2) controlling the free electron concentration in the high doping range (1E19/cm^3) by identifying and controlling self-compensation, and (3) suppressing DX-center formation by application of non-equilibrium processes such as ion-implantation and quasi defect Fermi level control. In addition, a wider doping range and better compensation control can be achieved by using alternative dopants such as Ge. Our group have been in the forefront of these developments by demonstrating not only novel point defect control schemes but also by demonstrating its capabilities such as the Schottky diode based on AlGaN and deep-UV lasers. The proposed research will develop a unique framework by which to realize the concept of dopant engineering in ultrawide bandgap semiconductors and related electronic materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.