Electrical properties of amorphous Cu doped InSe thin films

Abstract

In this study, we employed thermal evaporation under vacuum conditions to introduce copper dopants into amorphous InSe thin films. Our objective was to scrutinize the effects of varied copper doping concentrations on the structural, compositional, electrical, and photoelectrical properties of the films. Our observations indicated that copper doping did not induce discernible alterations in the amorphous morphology of the InSe films, yet it yielded notable enhancements in the material’s atomic stoichiometry. Notably, films subjected to both pristine conditions and 0.09 at. % copper doping exhibited extrinsic n-type conductivity behavior, while those doped with 0.42 at. % copper displayed a transition to p-type conductivity. Furthermore, our investigation encompassed electrical conductivity measurements conducted over a temperature range spanning from 100 to 320 K, elucidating the dominance of thermal excitation mechanisms at higher temperatures, and the prevalence of variable range hopping (VRH) processes at lower temperatures. The magnitude of copper dopants in the InSe matrix exerted discernible influence over impurity kinetics and VRH parameters, encompassing factors such as the degree of disorder, density of states proximate to the Fermi level, and average hopping distance. Additionally, our photoelectrical assessments unveiled that a nominal concentration of copper doping (0.09 at. %) yielded a remarkable augmentation of over 70% in the photoconductivity of the InSe films, underscoring its potential suitability for optoelectronic applications.