Jinno Riena, Chang Celesta S, Onuma Takeyoshi, Cho Yongjin, Ho Shao-Ting, Rowe Derek, Cao Michael C, Lee Kevin, Protasenko Vladimir, Schlom Darrell G, Muller David A, Xing Huili G, Jena Debdeep
School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA.
Department of Physics, Cornell University, Ithaca, NY 14853, USA.
Sci Adv. 2021 Jan 8;7(2). doi: 10.1126/sciadv.abd5891. Print 2021 Jan.
Ultrawide-bandgap semiconductors are ushering in the next generation of high-power electronics. The correct crystal orientation can make or break successful epitaxy of such semiconductors. Here, it is found that single-crystalline layers of α-(AlGa)O alloys spanning bandgaps of 5.4 to 8.6 eV can be grown by molecular beam epitaxy. The key step is found to be the use of m-plane sapphire crystal. The phase transition of the epitaxial layers from the α- to the narrower bandgap β-phase is catalyzed by the c-plane of the crystal. Because the c-plane is orthogonal to the growth front of the m-plane surface of the crystal, the narrower bandgap pathways are eliminated, revealing a route to much wider bandgap materials with structural purity. The resulting energy bandgaps of the epitaxial layers span a broad range, heralding the successful epitaxial stabilization of the largest bandgap materials family to date.
超宽带隙半导体正在引领下一代高功率电子学的发展。正确的晶体取向对于此类半导体外延生长的成功与否起着关键作用。在此，研究发现通过分子束外延可以生长出带隙在5.4至8.6电子伏特之间的α-(AlGa)O合金单晶层。关键步骤是使用m面蓝宝石晶体。外延层从α相到带隙较窄的β相的相变由晶体的c面催化。由于c面与晶体m面表面的生长前沿正交，较窄带隙的路径被消除，从而揭示了一条通往具有结构纯度的更宽带隙材料的途径。外延层最终的能带隙跨越了很宽的范围，预示着迄今为止最大带隙材料家族外延稳定的成功。
