Optical and electrical dynamics at the In/CuSe interfaces

Abstract

Herein, thin films of copper selenide are coated onto glass and 150 nm thick transparent indium substrates. The effect of indium substrates on the structural, morphological, compositional, optical, dielectric and electrical properties of CuSe are explored. Replacement of glass by indium, increased the crystallite and grain sizes, decreased the micro-strains, the stacking faults, the stress and the defect densities. Remarkable change in the shape of grains from wire like to rectangular shaped is forced by indium. Indium substrates also caused shrinkage in the energy band gap, enhanced the light absorbability and increased the dielectric constant values. The Drude-Lorentz analyses on the dielectric spectra have shown that the replacement of glass by indium increases the optical conductivity, increases the scattering time constant at femtosecond level and widens the range of plasma frequencies. On the other hand, dynamical electrical measurements which were carried out for In/CuSe/In devices, reveal the ability of using CuSe active media for fabrication of negative capacitance thin film transistors. Hopping conduction of charged particles over correlated barriers of height of 0.26 eV is dominant in the In/CuSe/In devices. The impedance spectroscopy analyses have shown that CuSe films can be used as bandstop filter appropriate for 5 G technologies.