EAGER: A novel route for high activation of implanted p-type regions in vertical Gallium Nitride devices.

到2030年，基于半导体的电力电子技术可以提高效率，节省1.2万亿千瓦时，减少约7.33亿吨二氧化碳的排放。在电力电子器件中实现宽禁带材料是进一步提高系统效率、减小器件尺寸和重量、提高可靠性和降低生命周期成本的最重要的革命。在各种宽禁带材料中，氮化镓（GaN）垂直功率器件被认为是下一代技术。尽管氮化镓横向功率器件取得了成功，但由于p-n结的限制和高掺杂p层的形成，延迟了垂直氮化镓功率器件的植入。虽然通过植入形成的n型结已经取得了成功，但通过植入形成的p型结仍然面临着关键的挑战。因此，开发一种有效的高掺杂p型工艺是实现高性能氮化镓器件的关键。本项目旨在通过采用固相外延工艺制备高掺杂p型结的新途径，解决氮化镓上p型掺杂的当前挑战。这为实现大电流和高压功率器件提供了一个独特的机会，使电力电子系统显著受益。这些进步的影响也可能推动超宽带隙器件的增强。提出的新型p掺杂可以使垂直氮化镓功率器件得到广泛采用，并有助于保持宽带隙半导体技术的领先地位和经济竞争力。本项目为本科生提供有关器件物理、加工和表征的动手研究经验。实验结果将纳入本科和研究生课程。本课题提出了一种采用固相外延工艺制备高掺杂p型氮化镓的新途径。这种固相外延过程包括通过适当的温度退火将含有目标p型掺杂剂的亚稳非晶区域转化为晶体区域。在其他半导体的先前研究中，固相外延已经显示出导致活性掺杂浓度的增加，大大超过固体溶解度限制，减少损伤，减少沟道，降低温度操作。所有这些特性对于垂直器件来说都是非常理想的，并为氮化镓固相外延的研究提供了必要的条件。该工艺将包括三个关键步骤：预非晶化注入，p型掺杂注入和中等温度退火以获得高活性浓度。该工艺有望通过适当的温度退火将含有目标p型掺杂剂的非晶态区域转化为晶体区域。再结晶温度和时间取决于晶体基质的取向和注入物质的种类和浓度。本研究旨在解决iii -氮化物器件面向大电流高压功率器件的根本问题，也可应用于新兴的超宽带隙材料。研究将包括分子动力学和工艺模拟、离子注入、固相外延退火优化、器件制造和结构表征（包括转移线方法结构和二极管结构）等多项任务，以评估固相外延工艺对氮化镓p结性能的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Semiconductor based power electronics enabled efficiency improvements could save 1.2 trillion kilowatt-hour by 2030, avoiding approximately 733 million metric tons of CO2. Implementation of wide bandgap materials in power electronic devices is the single most important revolution to further increase system efficiency, reduce the size and weight of devices, improve reliability, and reduce life cycle cost. Among various wide bandgap materials, gallium nitride (GaN) vertical power devices are conceived as a next generation technology. Despite the success of gallium nitride lateral power devices, the implantation of vertical gallium nitride power devices is delayed by limitation of p-n junction and highly doped p layer formation. While n-type junctions via implantation have gained success, p-type junctions formed via implantation are still facing key challenges. Hence, developing an effective highly doped p-type process is a critical need to enable high performance gallium nitride devices. This project aims to address the current challenges of p-type doping on gallium nitride by a novel route for highly doped p-type junctions using the process of solid phase epitaxy. This presents a unique opportunity for achieving high current and high voltage power devices to significantly benefit power electronic systems. The impact of these advances could also drive enhancements in ultra-wide bandgap devices. The proposed novel p-doping can enable wide adoption of vertical gallium nitride power devices and help maintain leadership in wide bandgap semiconductor technology and economic competitiveness. This project provides a hand-on research experience for undergraduate students on device physics, processing, and characterization. The experimental results will be incorporated into undergraduate and graduate courses. This project proposes a novel route for highly doped p-type in gallium nitride using the process of solid phase epitaxy after implantation. This solid phase epitaxy process involves the conversion of a metastable amorphous region containing the targeted p-type dopant into a crystalline region through modest temperature anneals. In prior work on other semiconductors, solid phase epitaxy has shown to result in increased active dopant concentration that is in great excess of the solid solubility limit, decreased damage, reduced channeling, and lower temperature operation. All these characteristics are highly desirable for vertical devices and warrant investigation of solid phase epitaxy in gallium nitride. The proposed process will involve three key steps: a pre-amorphization implantation, a p-type dopant implantation and a moderate temperature anneal to achieve high active concentration. This process is expected to convert the amorphous region containing the targeted p-type dopant into a crystalline region through modest temperature anneals. The recrystallization temperature and time depend on the orientation of the crystalline substrate and the type and concentration of implanted species. The proposed research aims to solve the fundamental problem in III-nitride devices towards high current and high voltage power devices and may also be applied towards emerging ultra-wideband gap materials. The research will be carried out in multiple tasks including molecular dynamic and process simulation, ion implantation, solid phase epitaxy anneal optimization, device fabrication and characterization of structures including transfer line method structures as well as diode structures to assess impact of solid phase epitaxy process on gallium nitride p-junction performance.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.