Calculation of the Density of Electronic States in the Valence Band from Experimental Interband Absorption Spectra of Amorphous Semiconductors

Experiments and calculations on the density of electronic states of amorphous carbon from an analytic form of the interband absorption spectrum are compared. The proportionality coefficient and energy width of the mobility gap are also determined as fit parameters from an analytic form of the interband absorption spectrum. For the interband absorption spectrum described by the Davis–Mott approximation method based on the Kubo–Greenwood formula for parabolic allowed bands an expression is obtained for determining the density of electronic states in the valence band of amorphous semiconductors. This expression and the interband absorption spectrum obtained from an experiment for amorphous carbon are used to demonstrate the feasibility of determining the densities of electronic states in the valence band.