First principle studies on the structural, thermodynamic and optoelectronic properties of Boron Bismuth: A promising candidate for mid-infrared optoelectronic applications

Abstract

A systematic study of the structural, thermodynamic, and optoelectronic properties of zinc blende (ZB) phase Boron Bismuth (BBi)is performed considering the full-potential linearized augmented plane wave (FPLAPW) basis sets based on the density functional theory (DFT) with the Perdew-Burke-Ernzerh of generalized gradient approximation (PBEsol) as exchange correlation (XC) functional and Modified Becke-Johnson (mBJ) potential. Structural optimization yields equilibrium lattice constant of 5.52 Å, bulk modulus of 81 GPa, and elastic stiffness constants. In addition to the fundamental thermodynamic properties and the elastic parameters, the optoelectronic properties such as complete electronic band diagram, electronic density of states (DOS), complex dielectric function, absorption coefficient, refractive index, optical conductivity, energy loss function, extinction coefficient, and reflectivity are evaluated. A smaller value of electronic effective mass as compared to hole effective masses leads to higher electron mobility in BBi which could be beneficial for fabricating electron based devices such as High Electron Mobility Transistors (HEMTs), nMOS, etc. Note that, unlike other B–V semiconductor, BBi exhibits a narrower direct-gap (Γ−Γ) of 422 meV which corresponds to mid-infrared wavelength of ~3 μm. Additionally, wider indirect-gap, and substantial spin orbit-coupling splitting of BBi can prove to be beneficial for fabricating LASERs and Photodetectors with minimal losses.