IN-SITU CORE-LEVEL PHOTOELECTRON-SPECTROSCOPY STUDY OF INDIUM SEGREGATION AT GAINAS/GAAS HETEROJUNCTIONS GROWN BY MOLECULAR-BEAM EPITAXY

In situ ultraviolet photoelectron spectroscopy (UPS) measurements have been performed at GaInAs/GaAs (100) interfaces. The high depth resolution of the UPS technique applied to the specific case of GaInAs/GaAs heterostructures [core-level photoelectron escape depth lambda almost-equal-to 2.1 monolayers (MLs)] is shown, yielding quantitative informations on the Ga/In atomic profiles at the ML scale. A surface segregation model is developped and the phenomenological segregation energy is obtained by UPS. This energy is used to generate potential energy profiles in a calculation of the energy of photoluminescence (PL) lines in GaInAs/GaAs quantum wells; the quantitative agreement with measured PL lines is very good.