Dependence of Structural, Compositional, Electrical, and Optical Properties of Sputtering-Deposited CdS Thin Films on Laser-Annealing Power

摘要

Cadmium sulfide (CdS) is one of the most attractive II-VI semiconductor materials in heterojunctional thin-film solar cells as a buffer layer in Cu(In, Ga)Se-2 photovoltaics and a window layer in cadmium telluride photovoltaics. Laser annealing with a diode laser (808 nm) using laser output powers from 0.7 to 1.0 W was carried out for sputtering-deposited CdS thin films in ambient N-2 gas for 15 s. The recrystallized CdS thin films grew along the H (002) plane at laser output power of 1.0 W after a phase transition from a mixed (metastable cubic and stable hexagonal) phase to the stable hexagonal phase at 0.9 W. Excellent optical transmittance of more than 88% with an appropriate band-gap energy (E-g) of 2.59 eV and reasonable resistivity on the order of 10(5) Omega.cm with a moderate carrier concentration in the range of 10(11)-10(12) cm(-3) were obtained in the laser-annealed CdS thin films for thin-film photovoltaic applications.