Modelling of novel bismide alloys for optoelectronic devices

The purpose of this thesis work is to investigate the electronic band structures of InAsBi/InAs, InPBi/InP, InSbBi/InSb and GaAsBiN/GaAs III-V materials by means of using model calculations. When bismuth and nitrogen atoms are incorporated into a III-V binary host semiconductor, bismuth and nitrogen impurity atoms occupy at localized energy levels which lies inside or close to the valence and conduction band, respectively. These localized impurity states interact with the extended valence and conduction band states of host alloy. This interaction causes a splitting in each of these band states of the light hole, heavy-hole, split-off band and conduction subbands into subbands of E+ and E- energy levels. The incorporation of dilute bismides and nitrides into host materials cause a reduction in band gap with increasing bismuth and nitrogen concentration, an increase in spin-orbit splitting energy with increasing bismuth concentration. These major modifications in band structure tends to eliminate or suppress optical loss mechanism, such as Auger recombination and Intervalence band absorption. Our theoretical analysis is based on the conduction band anti-crossing, C-BAC, model for incorporation of dilute nitrides and the valence band anti-crossing, VBAC, model for incorporation of dilute bismides to model the restructuring of valence and conduction bands.