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

研究的主要目标是用ArF激光器实现p-GaN层激活的GaN超结功率器件。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，SJ结构的制作非常困难。虽然这可以通过选择性离子注入来实现，但更好的方法是使用选择性准分子激光退火法，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激光对镁激活进行优化。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晶片的性能，并为SJ器件制造购买设计的光掩模。而第三阶段包括使用优化的晶片和激光参数来演示实际的SJ功率器件和表征。在我们收到Kakeni Startup几个月后，ArF激光退火pGaN的初步结果在2023年JSAP春季会议上公布。研究了ArF激光退火热处理对三叶草台面结构掺镁GaN的激活效果。霍尔测量表明，激光辐照的pGaN的电阻率随激光功率的增大而增大，这意味着激光功率可能对表面造成了损伤。首次成功地证明了采用三叶草台面结构的ArF激光退火法。需要进一步的研究来确认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.