面向 GaN 增强型器件应用的 p 型材料研究

   氮化镓（GaN）被誉为宽禁带半导体材料，它具有优良的物理特性，如宽带隙、高迁移率、高耐压和高热导率等，为各种行业的发展提供了强大的支持，如消费型电子、铁路、航空、汽车和工业设备等。在GaN HEMT的应用中，降低功耗及保证电路安全运行十分关键，因此增强型GaN HEMT的研究尤为重要。目前各种实现增强型GaN HEMT的方法都存在一定的不足。而基于p型GaN栅极的增强型器件由于工艺可重复性高、栅极稳定性较好等优势，得到了广泛关注，并且是目前唯一商用的增强型GaN器件方案。但是，具有p型GaN栅极的增强型器件对干法刻蚀工艺及镁的有效激活有很高的要求，其进一步发展也受此阻碍。因此，本课题从p型材料的角度出发，通过对一系列p型材料进行性能表征，针对更适合应用在增强型GaN HEMT中作为栅极的p型材料，做出一系列研究。

本课题通过对氧化亚铜、氧化亚镍和硼掺杂金刚石等一系列p型材料进行表征测试，详细分析了p型材料的生长速率、表面形貌、拉曼光谱和空穴浓度等信息。并且，通过将氧化亚铜、氧化亚镍等膜层应用在GaN HEMT栅极中，其阈值电压均实现了正偏。由于具有较好的薄膜性质，器件的开关电流比也得到了显著提升，这些结果都论证了p型氧化亚铜、氧化亚镍材料实现增强型器件的可行性。对于p型硼掺杂金刚石，本课题通过对单晶金刚石新型刻蚀工艺进行优化，有效改善了金刚石的表面形貌。此外，本课题优化了硼掺杂金刚石的欧姆接触工艺，实现了0.22 Ω·mm的金刚石上欧姆接触。这不仅为金刚石在GaN HEMT上应用奠定了基础，更为未来第四代半导体金刚石器的制备提供工艺技术支持。

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