INCORPORATION RATE VARIATION AT HETEROINTERFACES DURING III-V MOLECULAR-BEAM EPITAXY

Surface composition is known to influence cation and anion incorporation rates (IRs) during III-V molecular beam epitaxy (MBE) at high growth temperatures. Consequently, IRs can vary at heterointerfaces. The present study examines the temporal behavior of IRs during formation of AlGaAs/GaAs, GaInAs/GaAs and GaAsSb/GaAs heterointerfaces. Incorporation rates are deduced from the in situ detection via desorption mass spectrometry of the non-incorporated, or desorbed, fraction of the incident beam. Predicted compositional profiles are calculated from the observed IR variations and show significant enrichment in composition of one of the constituent species at the heterointerface. The predicted compositional profile for the GaInAs/GaAs system is qualitatively verified by X-ray diffraction and photoluminescence measurements on separately grown structures. These results are interpreted on the basis of simple first-order desorption considerations which incorporate strain-dependent activation energies for desorption.