砷化硼異質(zhì)結(jié)—潛在的光電薄膜和襯底材料

砷化硼是近期受到廣泛關(guān)注一種III-V半導(dǎo)體材料。研究表明，砷化硼具有可媲美金剛石的超高熱導(dǎo)率（~1300 Wm-1K-1），同時具有本征p型導(dǎo)電特性，并且可以長成毫米級的單晶。目前人們對砷化硼的基本物理性質(zhì)已經(jīng)開展了較為廣泛的研究。然而，從光電器件應(yīng)用考慮，不論作為功能薄膜還是襯底，砷化硼都必須與其他半導(dǎo)體材料形成異質(zhì)結(jié)，因此考察其異質(zhì)結(jié)相關(guān)特性十分重要。

來自美國密歇根大學(xué)的Emmanouil Kioupakis教授利用第一性原理計算，從薄膜和晶格匹配襯底兩種應(yīng)用考慮出發(fā)，研究了砷化硼異質(zhì)結(jié)相關(guān)性能，包括應(yīng)變對于能帶及載流子遷移率的影響，砷化硼與其他光電半導(dǎo)體的界面接觸等特性。他們發(fā)現(xiàn)施加各向同性的面內(nèi)應(yīng)變，不論是壓縮還是拉伸都會減小材料能隙，同時也會顯著提升載流子遷移率。值得注意的是，僅通過施加1%的雙軸拉應(yīng)變就能使電子和空穴沿面內(nèi)方向的室溫遷移率增加60%以上，如此強的應(yīng)變效應(yīng)在半導(dǎo)體材料中比較少見。這是由于應(yīng)變會分別減小砷化硼中電子的有效質(zhì)量以及空穴的帶間散射強度。另一方面，計算表明砷化硼的晶格常數(shù)與InGaN和ZnSnN2這兩種重要的光電半導(dǎo)體可以很好的匹配，并且可以與二者分別形成II型半導(dǎo)體接觸，可以形成良好的半導(dǎo)體異質(zhì)結(jié)。由于InGaN和ZnSnN2是本征n性導(dǎo)電，而砷化硼是本征p型導(dǎo)電，因此該異質(zhì)結(jié)具有良好光電特性，如光伏和電致發(fā)光等。結(jié)合砷化硼具有超高的晶格熱導(dǎo)率等特點，本研究表明砷化硼作為光電功能薄膜和薄膜襯底都具一定的應(yīng)用潛力。 該文近期發(fā)表于npj Computational Materials6:3 (2020)，英文標題與摘要如下。

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 ZnSnN2demonstrate the potential of BAs heterostructures for electronic and optoelectronic devices.