Wang Mengen, Mu Sai, Van de Walle Chris G
Materials Department, University of California Santa Barbara, Santa Barbara, California 93106-5050, United States.
ACS Appl Mater Interfaces. 2021 Mar 3;13(8):10650-10655. doi: 10.1021/acsami.0c22737. Epub 2021 Feb 22.
Epitaxial growth of aluminum gallium oxide is important for forming heterojunctions on GaO for high power electronics applications. We use density functional theory to explore the co-adsorption of Al, Ga, and O adatoms on the GaO(010) surface and the surface reconstructions during the growth of the alloy. We find that Al can adsorb in tetrahedral sites in many of the reconstructions. The migration barrier escaping from a tetrahedral site to an octahedral site is 1.72 eV for an Al adatom and 0.56 eV for a Ga adatom, indicating that Al diffusion is much more restricted than Ga diffusion on the surface. Our findings indicate that kinetic limitations are responsible for Al occupying both octahedral and tetrahedral sites in (AlGa)O, in spite of the fact that thermodynamically the octahedral site is preferred.
对于高功率电子应用中在氧化镓（GaO）上形成异质结而言，铝镓氧化物的外延生长至关重要。我们运用密度泛函理论来探究铝（Al）、镓（Ga）和氧（O）吸附原子在GaO(010)表面的共吸附情况以及合金生长过程中的表面重构。我们发现，在许多重构过程中，Al能够吸附在四面体位置。一个Al吸附原子从四面体位置迁移到八面体位置的迁移势垒为1.72电子伏特，而一个Ga吸附原子的迁移势垒为0.56电子伏特，这表明在表面上Al的扩散比Ga的扩散受到更多限制。我们的研究结果表明，尽管从热力学角度八面体位置更受青睐，但动力学限制导致Al在(AlGa)O中同时占据八面体和四面体位置。
