Surface Oxidation Properties in a Topological Insulator Bi2Te3 Film

Bi2Te3 films are grown on (111)-oriented GaAs substrates by using the hot wall epitaxy method and the surface oxidation properties in the films are investigated by x-ray photoelectron spectroscopy, Raman spectroscopy, and x-ray diffraction. The results show that the films are c-axis oriented. Two pairs of new peaks in the XPS spectra involved with the binding energies from Bi 4f and Te 3d electrons correspond to Bi?O?Te bonds. Besides the A11g, E2g and A21g vibration modes from Bi2Te3 films, two new peaks at 93.5cm?1 and 123cm?1 are observed in Raman spectra, which are assigned to ?-Bi2O3 and TeO2, respectively. Our results are helpful for analyzing the degradation mechanism of topological surface states in Bi2Te3.