In this work, the out‐diffusion and uphill‐diffusion of Mg inside (100) β‐Ga2O3 epilayers and substrates are reported. The Mg accumulates toward the (100) surface upon annealing under an oxidizing environment, whereas the concentration profile changes with annealing temperatures and durations. Furthermore, the out‐diffusion of Mg from the substrate into the epilayer is observed at temperatures above 800 °C, which continues during the film growth. The substitutional‐interstitial‐diffusion (SID) mechanism is suggested to be the driving mechanism for the former, and the latter is related to the diffusion of mobile Mg interstitials. The accumulation profile of Mg can be used to identify the interface between the epilayer and the substrate. Furthermore, significant differences in device performance are observed for power transistors fabricated on annealed and non‐annealed epitaxial β‐Ga2O3 wafers. Increased breakdown voltages of annealed samples are attributed to the Mg diffusion into the first few nanometers of the epitaxial layer close to the interface to the semi‐insulating substrate, leading to compensation of residual dopants (donors) in that region.

中文翻译：

---

高温退火下直拉生长 （100） β-Ga2O3 中 Mg 的向外扩散和上坡扩散及其对横向 MOSFET 器件的影响


在这项工作中，报道了 Mg 在 （100） β-Ga2O3 外延层和衬底内的向外扩散和上坡扩散。在氧化环境中退火时，Mg 向 （100） 表面积累，而浓度分布随退火温度和持续时间而变化。此外，在 800 °C 以上的温度下观察到 Mg 从衬底向外扩散到外延层，这在薄膜生长过程中持续存在。取代-间质-扩散 （SID） 机制被认为是前者的驱动机制，后者与移动 Mg 间质的扩散有关。Mg 的积累曲线可用于识别外延层和底物之间的界面。此外，在退火和非退火外延 β-Ga2O3 晶片上制造的功率晶体管在器件性能上观察到显著差异。退火样品击穿电压的增加归因于 Mg 扩散到靠近半绝缘衬底界面的外延层的前几纳米，导致该区域中残留掺杂剂（供体）的补偿。