Band alignment at surfaces and heterointerfaces of Al2O3, Ga2O3, In2O3, and related group-III oxide polymorphs: A first-principles study
Band alignment at surfaces and heterointerfaces of Al2O3, Ga2O3, In2O3, and related group-III oxide polymorphs: A first-principles study
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DOI：
10.1103/physrevmaterials.3.084605
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发表时间：
2019-08-23
影响因子：
3.4
通讯作者：
Oba, Fumiyasu
中科院分区：
文献类型：
--
作者：
Hinuma, Yoyo;Gake, Tomoya;Oba, Fumiyasu
利用第一性原理计算研究了Al 2 O3、Ga 2 O3和In 2 O3多晶型物以及三种相关的第三族氧化物Sc2 O3、Y2 O3和La 2 O3在非极性表面和异质界面的能带排列。一个非自洽的介电依赖的混合功能的方法是通过使用Perdew-Burke-Ernzerhof功能调整固体（PBESol），以加速带对齐评估，涉及表面和界面计算的半局部密度泛函计算的顶部。在所考虑的五种晶体结构中，即，Al 2 O3、Ga 2 O3、La 2 O3和其他的，在PBESol计算中，最低能量相分别是Al 2 O3、β-镓、κ-氧化铝、方铁锰矿（C型稀土）和A型稀土。在相同的晶体结构和表面终端内，电离电势通常按Al 2 O3、Ga 2 O3、In 2 O3、Sc2 O3、Y2 O3和La 2 O3的顺序降低。这种趋势被原子驰豫诱导的表面偶极增强，其中与O离子相比，较小的阳离子倾向于向体侧驰豫，而较大的阳离子倾向于向真空侧驰豫。在非弛豫表面的电离势和电子亲合势差是很好的指标的界面价和导带偏移，分别为Al 2 O3/Ga 2 O3的晶格参数的两个阶段的一个相对较小的失配。
The band alignments at nonpolar surfaces and heterointerfaces of Al2O3, Ga2O3, and In2O3 polymorphs, and three related group-III oxides, namely, Sc2O3, Y2O3, and La2O3, are investigated by using first-principles calculations. A non-self-consistent dielectric-dependent hybrid functional approach is adopted on top of semilocal density-functional calculations by using the Perdew-Burke-Ernzerhof functional tuned for solids (PBEsol) to accelerate the band alignment evaluation that involves surface and interface calculations. Among the five crystal structures considered, namely, corundum, beta-gallia, kappa-alumina, bixbyite (C-type rare earth), and A-type rare earth, the lowest energy phases are corundum, beta-gallia, A-type rare earth, and bixbyite for Al2O3, Ga2O3, La2O3, and the others, respectively, within PBEsol calculations. The ionization potential typically decreases in the order Al2O3, Ga2O3, In2O3, Sc2O3, Y2O3, and La2O3 within the same crystal structure and surface termination. This tendency is enhanced by the atomic relaxation-induced surface dipoles, where smaller cations tend to relax toward the bulk side compared to O ions, while larger cations tend to relax toward the vacuum side. The ionization potential and electron affinity differences at unrelaxed surfaces are good indicators of the interfacial valence- and conduction-band offsets, respectively, for Al2O3/Ga2O3 with a relatively small mismatch in the lattice parameters of the two phases.