Theoretical investigation of the thickness dependence of soft-x-ray emission from thin AlAs(100) layers buried in GaAs

Abstract
Ultrathin AlAs(100) layers of 1-, 2-, and 5-ML thickness buried in GaAs are investigated by ab initio calculations. Unique experimental soft-x-ray emission spectra are explained in terms of interface effects and changes with layer thickness are found in the density of states. Only the central layer in the 5-ML geometry is bulklike. A valence-band offset of 0.53 eV is also found for this structure, while no offset exists in the 1- and 2-ML cases. Very good agreement is achieved between theory and experiment.