Band Offsets, Optical Conduction, and Microwave Band Filtering Characteristics of γ‐In2Se3/CuO Heterojunctions

Abstract

Herein, the design and experimental characterization of γ‐In2Se3/CuO interfaces are considered. Thin films of γ‐In2Se3 are coated with thin layers of CuO at room temperature. The heterojunction device is structurally, morphologically, and optically characterized. It is observed that the coating of CuO onto γ‐In2Se3 engenders the formation of CuSe2 at the ultrathin interface. The γ‐In2Se3/CuO heterojunctions exhibit maximum possible conduction and valence band offsets of values 0.47 and 0.96 eV, respectively. The dielectric spectra display two dielectric resonance peaks at 2.96 and 1.78 eV. In addition, analyses of the optical conductivity spectra reveal accurate drift mobility and plasmon frequency values of 31.31 cm2 Vs−1 and 1.5 GHz, respectively. The ability of the device to control the signal propagation at gigahertz level is experimentally tested by the impedance spectroscopy technique which proved the ability of the device to behave as bandpass filters of notch frequency of 1.49 GHz. The γ‐In2Se3/CuO heterojunction devices are also observed to display terahertz cutoff frequency values of ≈24 THz in the infrared (IR) range of incident photon energy and ≈193 THz in the ultraviolet light range. The nonlinear optical performance of the device nominates it for use as terahertz/gigahertz band filters.