Nanoelectronic Modeling Lecture 33: Alloy Disorder in Bulk

This presentation discusses disorder in AlGaAs unstrained systems in bulk. Bandstructure of an ideal simple unit cellWhat happens when there is disorder?Concept of a supercellBand folding in a supercellBand extraction from the concept of approximate bandstructureComparison of alloy disorder with the virtual crystal approximationConfiguration noise, concentration noiseHow large does an alloy supercell have to be? When does the “bulk” condition occur?Learning Objectives:Bandedges and bandgaps are influenced by: Placement / configuration disorderConcentration noise Clustering System size is very important “bulk” starts at 100,000 atoms=> Nanostructures are not “bulk” => like quantum dots, nanowires, and quantum wells vary locally