HELIUM SCATTERING STUDY OF CLEAN AND OXYGEN COVERED GAAS(100)

摘要

The Ga-rich GaAs(100) surface and the adsorption of oxygen on this surface were investigated with He-diffraction, which is completely non-destructive and particularly sensitive to defects. Although the interpretation of the data is complex due to the large corrugation of the GaAs(100) surface, useful information is obtained. On the Ga-rich GaAs(100) surface two reconstructions are observed, the c(8 x 2) and the disordered (6 X 6) structure. We found a reversible phase transition between these reconstructions at a temperature of about 450 degrees C. The He-diffraction results support the model of the c(8 X 2) reconstruction proposed by Skala et al. Phys. Rev. B 48 (1993) 9138. A new model for the disordered (6 X 6) reconstruction is proposed. Oxygen is found to adsorb exclusively on Ga-terminated areas of the surface. On both reconstructions we found evidence for two chemisorption states of the oxygen. References: 19