Optical and structural properties of n− and p−InSe/In2O3 heterostructures

Abstract

In this work crystal structure and surface morphology, photoluminescence and fundamental optical absorption of n− InSe and p−InSe:Cd (0.05 at. %) single crystals and related heterojunctions with native oxide (In2O3) formed by surface oxidation are investigated. Oxidation-induced defects and Cd impurities shield exciton bonds, contribute to the increase of fundamental absorption, and determine photoluminescence features of InSe layer from the n (p)−InSe/In2O3 interface.Doping-induced impurity states and structural defects in the interfacial InSe layer are determining factors for the photon absorption at energies below the band gap.Impurity photoluminescence of interfacial InSe layer originates from donor−acceptor pair recombinations, for inter-pair distance much greater than thickness of elementary Se–In–In–Se packings.The violet−red emission band is determined by nonequilibrium charge carrier recombination in the interfacial In2O3 layer. Its intensity and shape are determined by structural defects at the p−InSe surface.