CHARACTERIZATION OF CdS:O THIN FILMS WITH DIFFERENT RATIO OF AMBIENT OXYGEN PREPARED BY RF MAGNETRON SPUTTERING AND ITS APPLICATION IN CdTe SOLAR CELLS

CdS:O thin films with different ratio of ambient oxygen have been prepared by RF magnetron sputtering. CdTe solar cells with CdS :O thin films as window layer have also been prepared. In order to investigate the effects of oxygen on CdS:O thin films and CdTe solar cells, X-ray diffraction, UV-Vis, X-ray photoelectron spectroscopy, Raman spectroscopy, EQE and I-V curve have been measured. The result shows ambient oxygen can promote the transform from crystalline to amorphous, thus lead to the increase of transmission value and band gap, which can benefit the improvement of short wave response of CdTe solar cell. However, generation of sulfate in CdS:O thin films inhibits the growth of CdSxTe1-x heterojunction interface and decreases fill factor and open-circuit voltage. The final result shows CdTe solar cells with CdS:O thin film with 0.2% ratio of oxygen as window layer has best performance and the efficiency is 12.93%.