Growth and characterization of InSe/Ge/InSe interfaces

Abstract

In the current study, we report the effect of insertion of a 200nm thick Ge film between two layers of InSe. The Ge sandwiched InSe films are studied by means of X-ray diffraction technique, energy dispersion X-ray spectroscopy attached to a scanning electron microscope, optical spectrophotometry and light power dependent photoconductivity. It was observed that, The InSe prefers the growth of InSe monophase when deposited onto glass and the growth of γ−In2Se3 when deposited onto InSe/Ge substrate. The three layers interface (InSe/Ge/γ−In2Se3) exhibits a Ge induced crystallization process at annealing temperature of 200°C. The optical analysis has shown that the InSe films exhibit a redshift upon Ge sandwiching. In addition, the conduction and valence bands offsets at the first interface (InSe/Ge) and at the second (Ge/γ−In2Se3) interface are found to be 0.55eV and 1.0eV, and 0.40eVand 1.38eV, respectively. Moreover, the photocurrent of the Ge sandwiched InSe exhibited higher photocurrent values as compared to those of InSe. On the other hand, the dielectric spectral analysis and modeling which lead to the identifying of the optical conduction parameters presented by the plasmon frequency, electron scattering time, free electron density and drift mobility have shown that the Ge sandwiching increased the drift mobility values from 10cm2/Vs to ∼42cm2/Vs. The main plasmon frequency also increased from 1.08 to 1.68GHz.