Effects of sputtering voltage and current on the composition and microstructure of the CIGS films prepared by one-step pulsed DC magnetron sputtering

Cu(In, Ga)Se₂ (CIGS) films were deposited at room temperature by one-step pulsed DC magnetron sputtering under different sputtering powers and pulse frequencies, and the effects of sputtering voltage and current on the composition and microstructure of the deposited GIGS films were systematically investigated. The results indicated the composition of the deposited films was seriously affected by the sputtering voltage and current. Moreover, a semiempirical formula was used to estimate the composition of the deposited CIGS films. On the whole, the estimated results can accord with the corresponding experimental results. In addition, the deposition rate (corresponding to sputtering current) is considered as the key factor of affecting the preferred orientation of the films in the present work, i.e., the preferred orientation changed from (112) to (220)/(204) with increasing deposition rate. Moreover, the electrical properties were measured for the CIGS films deposited at different sputtering powers, which were closely associated with the composition and microstructure of the films. The surface morphologies of the CIGS films deposited at different pulse frequencies were observed, which shown the granule size in the deposited films was mainly affected by the sputtering voltage.