CIGS thin film Deposition by Dual Ion Beam Sputtering (DIBS) system for Solar cell Applications

Abstract

Currently in solar cell market the cost effective Copper Indium Gallium Selenide (i.e. Cu(In,Ga)Se₂ or CIGS) thin film solar cells are showing most promising result among all other thin film solar cell technology. Typically, CIGS thin films for photovoltaic devices are deposited by co-evaporation or by deposition of the metals with or followed by treatment in a selenium environment. These methods have several disadvantages and complications. In this article, we describe an alternative of the same. We described the CIGS thin films of 1 μm thickness grown onto soda lime glass substrates by Dual Ion Beam Sputtering (DIBS) system from a single quaternary target with the composition of Cu (In_0.70Ga_0.30)Se₂ in a single step route without any additional selenization at different temperatures from 100 °C to 400 °C. These CIGS thin films are characterized for the solar cell application. The effects of the substrate temperature, on the structural and optical property of the CIGS layers were studied at room temperature using X-Ray Diffraction and UV–Vis-NIR spectrophotometer. The obtained results of the thin films includes the crystallinity, grain size, absorption coefficient and band gap energy etc. In structural property the preferred orientation of grains along highly oriented the (112) plane is observed. Crystallinity of the films improved with increasing substrate temperature as evidenced by the decrease of FWHM from 0.64 °C to 0.29 °C The strong influence of growth temperature on these properties were observed. We demonstrated that growth temperature can be varied in order to optimize the film properties and improve device performance.