Institute of Physics CAS, v. v. i., Cukrovarnická 10, 162 00 Prague 6, Czech Republic.
Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 11519 Prague 1, Czech Republic.
ACS Appl Mater Interfaces. 2023 Apr 19;15(15):19646-19652. doi: 10.1021/acsami.3c00799. Epub 2023 Apr 6.
This work suggests new morphology for the AlGaN/GaN interface which enhances electron mobility in two-dimensional electron gas (2DEG) of high-electron mobility transistor (HEMT) structures. The widely used technology for the preparation of GaN channels in AlGaN/GaN HEMT transistors is growth at a high temperature of around 1000 °C in an H atmosphere. The main reason for these conditions is the aim to prepare an atomically flat epitaxial surface for the AlGaN/GaN interface and to achieve a layer with the lowest possible carbon concentration. In this work, we show that a smooth AlGaN/GaN interface is not necessary for high electron mobility in 2DEG. Surprisingly, when the high-temperature GaN channel layer is replaced by the layer grown at a temperature of 870 °C in an N atmosphere using TEGa as a precursor, the electron Hall mobility increases significantly. This unexpected behavior can be explained by a spatial separation of electrons by V-pits from the regions surrounding dislocation which contain increased concentration of point defects and impurities.
这项工作提出了一种新的 AlGaN/GaN 界面形态，可提高高电子迁移率晶体管（HEMT）结构中二维电子气（2DEG）的电子迁移率。在 AlGaN/GaN HEMT 晶体管中制备 GaN 沟道的常用技术是在 H 气氛中约 1000°C 的高温下生长。这些条件的主要原因是旨在为 AlGaN/GaN 界面制备原子级平坦的外延表面，并实现碳浓度尽可能低的层。在这项工作中，我们表明，对于 2DEG 中的高电子迁移率，平滑的 AlGaN/GaN 界面不是必需的。令人惊讶的是，当用 TEGa 作为前体在 N 气氛中于 870°C 的温度下生长的层代替高温 GaN 沟道层时，电子霍尔迁移率显著增加。这种意外的行为可以通过电子从包含点缺陷和杂质浓度增加的位错周围区域的 V 形凹陷中分离出来来解释。
