X-RAY PHOTOEMISSION CHARACTERIZATION OF INTERFACE ABRUPTNESS AND BAND-OFFSET OF GA0.5IN0.5P GROWN ON GAAS

We have studied by angle resolved x-ray photoemission spectroscopy (XP S) the interface between Ga0.5In0.5P and GaAs grown by gas source mole cular beam epitaxy. For cations, we show that the interface is abrupt for a growth temperature of 400 degrees C and that indium segregation is effective at 500 degrees C but less than that in GaInAs at the same temperature. For anions, growth of the two layers in rapid succession results in the incorporation of an excess of arsenic in the GaInP epi layers and a diffuse interface. As soon as these predominant experimen tal effects are suppressed, the abruptness of the interface is limited by a weak arsenic surface segregation. For this quasi-abrupt interfac e, we report a valence band offset of approximate to 0.3 eV as determi ned by XPS. (C) 1998 American Institute of Physics. [S0021-8979(98)047 16-1].