(Ga, In)(N, As)-fine structure of the band gap due to nearest-neighbor configurations of the isovalent nitrogen

Abstract

An intrinsic property of quaternary alloys ${A}_{1\ensuremath{-}y}{B}_{y}{C}_{1\ensuremath{-}x}{D}_{x} (x\ensuremath{\approx}1--3%)$ with D being an isovalent trap is reported: a set of discrete band gaps occurs due to substitution of the isovalent trap D on sites with different nearest-neighbor environments. Exemplary, this phenomenon is demonstrated for (Ga,In)(N,As) by experiment and explained by tight-binding supercell calculations. The band gap of this nitrogen-poor alloy is blueshifted by simply moving the nitrogen isovalent traps from Ga-ligand rich sites to In-ligand rich sites, without changing the alloy composition.