Effect of Deposition of Submonolayer Cs Coatings on the Density of Electronic States and Energy Band Parameters of CoSi2/Si(111)

Using the methods of ultraviolet photoelectron spectroscopy, light absorption spectroscopy, and true secondary electrons, the effects of deposition of Cs atoms with a thickness of   1 monolayer on the density of electronic states in the valence and conduction bands, energy band parameters, and quantum yield of photoelectrons have been studied for the first time. It has been established that when cesium is deposited on the surface of cobalt disilicide with a thickness of   1 monolayer, the value of Еg and the positions of the maxima of the density of states of valence electrons practically do not change, the work function of photoelectrons decreases to 3 eV, and the quantum yield of photoelectrons increases by a factor of 3 or more. After deposition of Cs on the surface of CoSi2/Si (111) with a thickness of d  500 Å, the yield of true secondary electrons into vacuum increases, and the beginning of the spectrum shifts towards lower energies by ~ 2.4 eV, i.e., the potential barrier (electron affinity ) decreases by 2.4 eV. The decrease in Ф is mainly due to the decrease in the width of the conduction band . In this work, for the first time, the positions of the maxima of the density of free electron states in the conduction band of CoSi2 are experimentally determined. It is shown that the maxima are located at energies of 0.8 and 1.9 eV below the vacuum level.