Optical interactions in the InSe/CdSe interface

Abstract

In this work, the structural and optical properties of the InSe/CdSe heterojunction are investigated by means of X-ray diffraction and ultraviolet-visible light spectrophotometry techniques. The hexagonal CdSe films that were deposited onto amorphous InSe and onto glass substrates at a vacuum pressure of 10−5 mbar, exhibited interesting optical characteristics. Namely, the absorption, transmission, and reflection spectra that were recorded in the incident light wavelength range of 300–1100 nm, for the InSe, CdSe, and InSe/CdSe interface revealed direct allowed transition energy bandgaps of 1.44, 1.85, and 1.52 eV, respectively. The valence-band offset for the interface is found to be 0.36 eV. On the other hand, the dielectric constant spectral analysis displayed a large increase in the real part of the dielectric constant associated with decreasing frequency below 500 THz. In addition, the optical conductivity spectra that were analyzed and modeled in accordance with the Drude theory displayed a free-carrier average scattering time of 0.4 fs and a drift mobility of 6.65 cm2 V−1 s−1 for the InSe/CdSe interface. The features of this interface nominate it as a promising member for the production of optoelectronic Schottky channels and as thin-film transistors.