Above bandgap one-photon excitation induced nonlinear absorption behavior of InTe

Abstract

In an attempt to investigate the nonlinear absorption properties of amorphous InTe semiconductors, three different thicknesses of 30 nm, 60 nm and 90 nm thin films were deposited by the vacuum evaporation method. Bandgap energies and Urbach energies were obtained from the linear absorption spectrum. While the change in thickness and doping led to slight changes in bandgap energies as 0.08 eV, significant increases in Urbach energies were obtained for thicker and doped films. A theoretical model accounting one photon absorption, excited state absorption, and saturation of each process was utilized to derive the transmittance in open aperture Z-scan data. The values of nonlinear absorption coefficient and saturation intensity threshold were obtained from the model and the interplay between excited state absorption and saturable absorption was explained by proposing an energy band diagram containing the contribution of defect states to the nonlinear absorption behavior of amorphous semiconductors.