GaAsBi alloys for photovoltaic and thermophotovoltaic applications

Abstract

In this study, we focus our attention on GaAs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> , a ternary compound with decreasing bandgap as the Bismuth (Bi) content is increased. GaBi belongs to a group of materials known as semi-metals and possesses an optical below zero: This implies that the material bandgap can theoretically change from 1.42 eV (x=0) to -1.45 eV (x=1). Presented in this study is an examination of how the band structure and associated properties such as the optical bandgap and lattice constant of GaAsBi change with varying Bi content. GaAsBi is examine through the use of density functional theory based simulations and compared to experiment and simulation from the literature. Changing the Bi content allows for a number of candidate lattice-matched substrates including GaAs, Ge, and InP. Finally, the simulated performance of a single junction GaAsBi solar photovoltaic cell is also compared to a Germanium cell under identical standard conditions.