Abstract
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.
Highlights
Boron arsenide (BAs) is an attractive electronic material due to its ultra-high thermal conductivity (~1300 W m–1 K–1),[1,2,3] native ptype dopability,[4] and the availability of millimeter-size single crystals as substrates for thin-film growth.[3,5,6] Following the experimental validation[1,2,3] of the theoretical prediction[7,8] of its ultra-high thermal conductivity, research efforts have focused on its growth and fundamental characterization.[9]
Strain effects on the band structure and absolute band positions We first examine the effects of strain on the band structure along the Γ–X and Γ–Z directions, which include the conduction band minimum (CBM) and valence band maximum (VBM)
The X and Z directions are equivalent by symmetry, and the conduction band minima along the Γ–X and Γ– Z directions are degenerate (Fig. 2a)
Summary
Boron arsenide (BAs) is an attractive electronic material due to its ultra-high thermal conductivity (~1300 W m–1 K–1),[1,2,3] native ptype dopability,[4] and the availability of millimeter-size single crystals as substrates for thin-film growth.[3,5,6] Following the experimental validation[1,2,3] of the theoretical prediction[7,8] of its ultra-high thermal conductivity, research efforts have focused on its growth and fundamental characterization.[9]. Two important degrees of freedom for thin-film engineering in device architectures are mechanical strain and band alignment. Strain arising from epitaxial mismatch strongly affects the electronic properties of materials, including the band gap,[17] band alignments,[18] effective masses,[19] and mobility.[20,21] Though the epitaxial growth of BAs thin films has not been demonstrated yet, it should be feasible under growth conditions that replicate the established chemical vapor transport growth procedure. Candidate tetrahedrally bonded substrate materials for thin-film growth on the (111) plane of BAs are ZnO (3.249 Å22), GaN (3.189 Å23), or GaAs (3.997 Å24), while for (001)-oriented BAs thin films, candidate substrates are (001) oriented rutile TiO2 (4.59 Å25) or MgF2 (4.64 Å26), which result in epitaxial strains ranging from −6% to +15% (Fig. 1a). The effects of mechanical strain on the electronic properties of BAs are unknown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
