Preparation of ZnS thin films by using photoassisted MOCVD

Abstract

Zinc sulfide thin films were grown by using both normal metal-organic chemical vapor deposition (MOCVD) and photoassisted MOCVD with diethylzinc and t-butylthiol as sources for the zinc and the sulfur, respectively. The effects of UV irradiation and reactor chamber pressure on the film growth were investigated. The basic physical properties of the ZnS thin films grown by using MOCVD were also investigated with X-ray diffraction, optical absorption, and Raman spectroscopy. The growth rate of the ZnS thin films grown by using photoassisted MOCVD were improved by about 28% compared to that of the films grown by using normal MOCVD. The growth rate also increased with increasing reactor chamber pressure. The energy band gap obtained from the optical absorption spectrum was 3.58 eV. MOCVD-grown ZnS thin films were hexagonal (lattice constants: a = 0.382 nm and c = 0.626 nm). In the Raman spectrum, the A1 and the E1 transverse peaks (A1(TO) and E1(TO)) were observed at 277 cm−1, and the A1 and the E1 longitudinal peaks (A1(LO) and E1(LO)) were observed at 354 cm−1.