Characterization of ZnS films on different substrates by pulsed laser deposition

Abstract

ZnS films were deposited on Si and quartz substrates via pulsed laser deposition, and the structure, morphology and photoelectric characteristics of as-deposited and annealed ZnS films were compared. XRD results show that ZnS films are polycrystalline, and the intensity of peak at 28.4° on Si is larger, with a narrower FWHM. AFM topographies show that the surface of ZnS films becomes rough after annealing, and the roughness on quartz is obviously larger than that on Si. The transmittance of ZnS films in the visible light region reaches 80%, which indicates that ZnS is suitable for making transparent conductive films. PL spectra show that there are two luminescence peaks at 425 and 445 nm related to the intrinsic defect levels of ZnS. Due to the small lattice mismatch, PL intensity on Si is significantly weaker than that on quartz. I-V characteristics of ZnS/p-Si heterojunctions show typical p-n junction diode-like rectification behavior.