Composition and Band Gap Controlled AACVD of ZnSe and ZnS x Se 1-x Thin Films Using Novel Single Source Precursors

Abstract

Polycrystalline thin films of ZnSe and ZnSxSe1−x have been deposited on glass substrates by Aerosol Assisted Chemical Vapour Deposition (AACVD) from bis(diethyldiselenocarbamato)zinc(II) and a 1:1 and 1:0.75 mixtures of bis(diethyldiselenocarbamato)zinc(II) and bis(diethyldithiocarbamato)zinc(II) as precursors. All films were characterized by p-XRD, SEM, EDX, Raman spectroscopy, photoluminescence (PL and UV/Vis spectroscopy. The band gap of pure ZnSe thin films was found to be 2.25 whereas the band gap of ZnSxSe1−x films varied from 2.55 to 2.66 eV depending on the sulfur content in the films. PL emission spectra showed a clear blue shift for ZnSxSe1−x films compared to ZnSe due to the sulphur content in the films which increase the band gap. The band gap of ZnSSe can be controlled by sulfur to selenium ratio in the alloy. The morphology of the ZnSe thin films changed from small randomly shaped crystallites to triangles whereas the morphology of ZnSxSe1−x was mainly based on cuboids.