Synchrotron Methods of the Conduction Band Electronic Structure Analysis

Abstract

The experimental and theoretical studies of the density of states for unoccupied conduction band are a valid source of knowledge on the electronic structure of condensed matter. Among known analytical methods of density of states for unoccupied states a significant place is occupied by the methods with the use of intensive synchrotron radiation beam. Adequately chosen monochromatic beam excites electrons from the occupied core states or the valence band to unoccupied states in the conduction band. The most universal experimental method for the studies of the unoccupied conduction band is the X-ray absorption near edge structure analysis for X-ray edges of the constituent atoms of the material. A satisfying description of the unoccupied conduction band density of states can be also reached by the analysis of reflectivity coefficient in the vacuum ultraviolet (above 10 eV). The photoelectron energy distribution curves elaborated by the constant initial state and constant final state procedures deliver valuable information on the high excited states of conduction band. In the paper the menaces of the correct interpretation of the experimental results will be discussed. The efficiency of the unoccupied conduction band density of states studies with application of X-ray absorption near edge structure and analysis of reflectivity coefficient of light will be presented on the basis of several binary and ternary semiconductor compounds of II–VI group with transition metals as well as of some other compounds. To avoid a misinterpretation of the experimental results, the data were compared and discussed with an adequate theoretical band structure calculation.