Measurement of core level and band offsets at the interface of ITO/Hg3In2Te6(1 1 0) heterojunction by synchrotron radiation photoelectron spectroscopy

Abstract

The Indium Tin Oxide (ITO) film was deposited on the surface of Hg3In2Te6 (short for MIT) (110) for the fabrication of ITO/MIT(110) heterojunction by using the pulsed laser deposition method. In situ X-ray photoelectron spectroscopy was utilized to examine the band offsets and core level of ITO/MIT(110) heterojunctions. The result showed that the valence band maximum of ITO films and MIT(110) were 1.6eV and 0.6eV, respectively. Meanwhile, it was found that the binding energy of Te 3d, Sn 3d and Hg 4f remained unchanged during the ITO deposition process. However, the binding energy of O 1s and In 3d5/2 increased about 0.3eV and 0.2eV, respectively, with the thickness increasing of ITO film from 3.5nm to 5nm. This may due to the elements diffusion at the interface region during the film growing process. According to the core level spectrum, it can be speculated that no significant chemical reaction occurred at the interface of ITO/MIT(110). In addition, the valence band offset of the ITO/MIT(110) heterojunction can be calculated to be −1±0.15eV by the means of the photoelectron spectroscopy methods. The conduction band offset is deduced to be −3.96±0.15eV from the known valence band offset value, indicating that the band offsets of ITO/MIT(110) heterojunction is a type-II band alignment.