Effect of Substrate Temperature on One-Step Magnetron-Sputtered Cu(In,Ga)Se<sub>2</sub> Thin Films for Solar Cells

Abstract

CIGS thin films were deposited on soda lime glass by one-step magnetron sputtering using a single quaternary-CIGS target in stoichiometric proportions. The influences of substrate temperature on the structural, optical, and electrical properties of Cu(In,Ga)Se2 (CIGS) thin films were investigated. The phase structure of CIGS thin films was characterized by X-ray diffraction (XRD). The morphology and thickness of CIGS thin films were observed by Scanning Electron Microscope (SEM). The absorption coefficient of CIGS thin films was measured by Ultraviolet-visible Spectrophotometer. Four-point probe method was used to test the resistivity of CIGS thin films. Based on the results of characterization, the increase in crystallite size of CIGS was found to be significantly noticeable with increasing substrate temperature. UV-vis measurement analysis suggested that CIGS thin films deposited at different substrate temperatures had high absorption coefficient (~104 cm-1) and optical band gap (1.07-1.23 eV). The substrate temperature dependence of the resistivity of the films indicated that the resistivity of the films fall to about 0.5 Ω۰cm as the substrate glass was heated up to 300 °C.