Oxidation and oxygen thermal desorption mechanism on narrow-gap IV-VI semiconductor PbTe(111) surface

Abstract

Oxidation and thermal desorption mechanism on the PbTe(111) surface were investigated using X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and low- energyelectron diffraction (LEED). The initial cleaning of the surface by 500 VAr + sputtering followed by annealing at 250 °C yielded a perfect (1×1) PbTe(111) surface. XPS measurements showed that PbO 2, PbO, and TeO 2 were present at the PbTe(111) surface after air exposure for 2 days, and the intensity ratio of Te 3d 5/2 and Pb 4f 7/2 increased rapidly compared to that of the clean PbTe(111) surface, indicating Te depletion and Pb enrichment of the surface. XPS and STM measurements showed that the thickness of the oxide layer was more than 2 monolayers (MLs). During thermal treatment, the core levels of PbO 2 and TeO 2 disappeared and the intensity of the O 1s core level decreased, indicating surface decomposition of PbO 2 and TeO 2, and desorption of oxygen, whereas PbO was still present on the surface after annealing at up to 350 °C. © Editorial office of Acta Physico-Chimica Sinica.