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 A(1g)(1), E-g(2) and A(1g)(2) vibration modes from Bi2Te3 films, two new peaks at 93.5 cm(-1) and 123 cm(-1) are observed in Raman spectra, which are assigned to alpha-Bi2O3 and TeO2, respectively. Our results are helpful for analyzing the degradation mechanism of topological surface states in Bi2Te3.