DOMINATION OF ADATOM-INDUCED OVER DEFECT-INDUCED SURFACE-STATES ON P-TYPE GAAS(CS,O) AT ROOM-TEMPERATURE

The unpinned behavior of the Fermi level, photovoltage, and recombinat ion velocity is demonstrated experimentally at room temperature for a p-type GaAs(Cs,O) interface by means of photoreflectance and photolumi nescence techniques. This behavior manifests itself as the multiple re versible swicthing of surface band bending, the amplitude of photorefl ectance, and photoluminescence intensity under alternate deposition of cesium and oxygen on a clean surface of expitaxial p-type GaAs layers . The results prove that cesium-induced donorlike surface states domin ate over defect-induced states.