X-Ray Photoelectron Spectroscopy of Ferroelectrics

The paper presents the X-ray photoelectron spectra (XPS) of the valence band (VB) and of the principal core levels (CL) for SbSI-type and incommensurate TlInS ₂ single crystals. Form and electronic structure of the VB and CL splitting in the quasi-one-dimensional SbSI, SbSeI and BiSI, and in the incommensurate (IC) phase of TlInS ₂ crystals are discussed. Experimentally obtained energies were compared with the results of theoretical ab initio calculations. Large shifts (3 ÷ 5 eV) in the CL binding energies in SbSI show a strong dependence on the surface crystallographic plane. The splitting of the CL was also obtained in the IC phase of TlInS ₂ crystals.

Keywords:

• Electron structure
• SbSeI
• BiSI
• XPS
• binding energies
• chemical schifts

Acknowledgments

This work was performed, in part, within the framework of the Lithuanian-Ukrainian project “Development and studies of new materials for information technologies, acousto-, opto-and nanoelectronics.”