INVESTIGATION OF THE VALENCE BAND OF GERMANIUM DOPED WITH IRON BY MEANS OF X-RAY PHOTOELECTRON SPECTROSCOPY AND DENSITY FUNCTIONAL THEORY

The electron structure of a double layered Ge-Fe system has been studied by combination of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). The double Ge-Fe layered system with a thickness of 7.5 nm with equal content of Ge and Fe atoms was formed in ultra-high vacuum by annealing of Ge and Fe films consequently formed on the Mo(110) substrate. According to the photoelectron measurements carried out in the range of binding energy values of 0-200 eV, there is a shift in the spectral lines of both Ge and Fe relative to the values characteristic of Ge and Fe separately, which is consistent with the results of the DFT calculations. The observed correspondence between the nature of the energy shifts of the electron orbitals and the qualitative agreement in the absolute values of these shifts obtained by both methods indicates the promise of this approach for detailed tuning of the structural and electronic properties of germanium doped with iron and other metals.