Density of states and interband light absorption in Y2O3 and Sc2O3 thin films

The long-wavelength edge of the fundamental absorption band of thin Y2O3 and Sc2O3 films obtained by the method of discrete evaporation in vacuum is investigated. On the basis of its temperature dependence, the excitons - phonon interaction is investigated, which made it possible to interpret the absorption edge as the absorption of self-trapped excitons. To analyze the experimental results, we used a model of a heavily doped or defective semiconductor in the quasi-classical approximation. The use of this model made it possible to estimate the radius of the ground electronic state a and the screening radius rS and the concentration of free charge carriers N in the films under study.