Copper doping effects on the optical properties of InSe thin films رسالة ماجستير

Abstract

In this thesis, we attempted to improve the optical and dielectric performance of InSe thin films through doping of copper into the structure of InSe. The InSe thin films which are prepared by the thermal evaporation technique under vacuum pressure of 10°% mbar onto glass substrates were structurally and optically characterized by means of X-ray difraction and optical spectrophotometry techniques. The doping content in the films was scanned by the energy dispersive sp opy technique. Undoped and Cu-doped InSe thin films with doping content of l.5 at%% and 3.0 a% were studied and analyzed. The EDX analyses has shown that while the formed films preferred the InSe monophase in the presence of Cu InsoSeyo is preffered. lt was observed that at this level of doping the amorphous nature of the films is not altered. However, the optical transitions which revealed energy band gap values of 1.38 eV for the undoped films is charged from indirect to direct type upon doping. The doping of 3.0 a% increased the value of energy band gap by 29% and decreased the width of the energy band in InSe by 76% indicating better optical performance. In addition, the doping with l.5 % improves both of the dielectric and conduction properties. The dielectric constant at resonance energy increased ftom l2 to l5 and the drift mobility

increased from 45 to 55 cm’/Vs upon doping.