Development of GaN superjunction devices with pGaN ArF laser activation for high power application

本研究的主要目标是利用ArF激光实现氮化镓超结（GaN SJ）功率器件。这将是这种制造方法的原始概念证明。GaN SJ器件是下一代功率器件的候选器件。然而，由于需要交替的p层和n层，制造SJ结构是非常困难的。虽然这可以通过选择性离子注入来实现，但更优雅的方法是使用选择性准分子激光退火，它可以通过激光照射来定义p区（p-GaN）。研究实施计划包括三个阶段。第一阶段包括使用ArF激光对mg激活进行优化。第二阶段包括反馈优化的激光参数，以进一步调整下一批GaN晶圆的性能，并购买设计的光掩膜用于SJ器件的制造。第三阶段使用优化后的晶圆和激光器参数对SJ功率器件进行了实际演示和表征。在我们收到Kakenhi Startup几个月后，在JSAP 2023春季会议上公布了ArF激光退火pGaN的初步结果。研究了ArF激光退火对三叶草结构的掺镁氮化镓的活化效果。通过霍尔测量，激光辐照pGaN的电阻率随激光功率的增加而增加，表明激光功率可能对表面产生了损伤。首次成功地演示了利用三叶草台面结构的ArF激光退火方法。需要进一步的研究来证实pGaN的激活。

Main goal of the study is to realize Gallium nitride superjunction (GaN SJ) power device with p-GaN layer activated using an ArF laser. This will be an original proof of concept for this fabrication method. GaN SJ device is a candidate for next generation power devices. However, fabrication of SJ structure is very difficult, due to the alternating p- and n- layers needed. Although this can be achieved by selective ion implantation, a more elegant approach is to use selective excimer laser annealing, which can define the p-region (p-GaN) by laser irradiation. Research implementation plan includes three phases. Phase 1 includes optimization of the Mg-activation using ArF laser. Phase 2 includes feedback of optimized laser parameters to further tune the next batch of GaN wafer properties, and purchase the designed photomask for SJ device fabrication. And phase 3 includes the used of the optimized wafer and laser parameters to demonstrate actual SJ power device and characterization. Few months after we received Kakenhi Startup, initial results of ArF laser annealing of pGaN is presented during the JSAP spring conference 2023. The effectiveness of ArF laser annealing in the activation of Mg-doped GaN using cloverleaf mesa structure is investigated. Using hall measurement, laser irradiated pGaN showed that the resistivity increases as laser power is increased, implying that the laser power may have damage the surface. ArF laser annealing method using cloverleaf mesa structure is first successfully demonstrated. Further investigation needed to confirm pGaN activation.