THE ELECTRONIC-STRUCTURE OF ALYGAXIN1-X-YAS ALLOYS AND RELATED HETEROJUNCTIONS

The dependences on composition of the bond lengths and energy bands of AlyGaxIn1-x-yAs quaternary alloys are calculated on the basis of tigh t-binding theory under the virtual-crystal approximation. For a AlyGax In1-x-yAs quaternary alloy lattice matched to InP, a type ll staggered band line-up is observed when the Al composition is larger than 24%. At this point the conduction band discontinuity of AlyGaxIn1-x-yAs/InP heterostructures disappears. The effective electron mass associated w ith the conduction band minimum is estimated on the basis of the k . p theory, and is in good agreement with the cyclotron resonance experim ental results. The relative conduction band discontinuity Delta E-c/De lta E-g is determined to be 72.2% for In0.53Ga0.47As/In0.52Al0.48As. T he band offsets of the related heterojunctions are calculated, and com pared with experimental and previous theoretical results.