砷化硼异质结—潜在的光电薄膜和衬底材料

砷化硼是近期受到广泛关注一种III-V半导体材料。研究表明，砷化硼具有可媲美金刚石的超高热导率（~1300 Wm-1K-1），同时具有本征p型导电特性，并且可以长成毫米级的单晶。目前人们对砷化硼的基本物理性质已经开展了较为广泛的研究。然而，从光电器件应用考虑，不论作为功能薄膜还是衬底，砷化硼都必须与其他半导体材料形成异质结，因此考察其异质结相关特性十分重要。

来自美国密歇根大学的Emmanouil Kioupakis教授利用第一性原理计算，从薄膜和晶格匹配衬底两种应用考虑出发，研究了砷化硼异质结相关性能，包括应变对于能带及载流子迁移率的影响，砷化硼与其他光电半导体的界面接触等特性。他们发现施加各向同性的面内应变，不论是压缩还是拉伸都会减小材料能隙，同时也会显著提升载流子迁移率。值得注意的是，仅通过施加1%的双轴拉应变就能使电子和空穴沿面内方向的室温迁移率增加60%以上，如此强的应变效应在半导体材料中比较少见。这是由于应变会分别减小砷化硼中电子的有效质量以及空穴的带间散射强度。另一方面，计算表明砷化硼的晶格常数与InGaN和ZnSnN2这两种重要的光电半导体可以很好的匹配，并且可以与二者分别形成II型半导体接触，可以形成良好的半导体异质结。由于InGaN和ZnSnN2是本征n性导电，而砷化硼是本征p型导电，因此该异质结具有良好光电特性，如光伏和电致发光等。结合砷化硼具有超高的晶格热导率等特点，本研究表明砷化硼作为光电功能薄膜和薄膜衬底都具一定的应用潜力。   该文近期发表于npj Computational Materials 6: 3 (2020)，英文标题与摘要如下。  

Boron arsenide heterostructures: lattice-matched heterointerfaces and strain effects on band alignments and mobility

Kyle Bushick, Sieun Chae, Zihao Deng, John T. Heron& Emmanouil Kioupakis

BAs is a III–V semiconductor with ultra-high thermal conductivity, but many of its electronic properties are unknown. This work applies predictive atomistic calculations to investigate the properties of BAs heterostructures, such as strain effects on band alignments and carrier mobility, considering BAs as both a thin film and a substrate for lattice-matched materials. The results show that isotropic biaxial in-plane strain decreases the band gap independent of sign or direction. In addition, 1% biaxial tensile strain increases the in-plane electron and hole mobilities at 300 K by >60% compared to the unstrained values due to a reduction of the electron effective mass and of hole interband scattering. Moreover, BAs is shown to be nearly lattice-matched with InGaN and ZnSnN2, two important optoelectronic semiconductors with tunable band gaps by alloying and cation disorder, respectively. The results predict type-II band alignments and determine the absolute band offsets of these two materials with BAs. The combination of the ultra-high thermal conductivity and intrinsic p-type character of BAs, with its high electron and hole mobilities that can be further increased by tensile strain, as well as the lattice-match and the type-II band alignment with intrinsically n-type InGaN and ZnSnN2 demonstrate the potential of BAs heterostructures for electronic and optoelectronic devices.