Low temperature synthesis of wurtzite zinc sulfide (ZnS) thin films by chemical spray pyrolysis

Abstract

Zinc sulfide (ZnS) thin films have been synthesized by spray pyrolysis at 310 °C using an aqueous solution of zinc chloride (ZnCl2) and thioacetamide (TAA). Highly crystalline films were obtained by applying TAA instead of thiourea (TU) as the sulfur source. X-ray diffraction (XRD) analyses show that the films prepared by TAA contained a wurtzite structure, which is usually a high temperature phase of ZnS. The crystallinity and morphology of the ZnS films appeared to have a strong dependence on the spray rate as well. The asymmetric polar structure of the TAA molecule is proposed to be the intrinsic reason of the formation of highly crystalline ZnS at comparatively low temperatures. The violet and green emissions from photoluminescence (PL) spectroscopy reflected the sulfur and zinc vacancies in the film. Accordingly, the photodetectors fabricated using these films exhibit excellent response to green and red photons of 525 nm and 650 nm respectively, though the band gaps of the materials, estimated from optical absorption spectroscopy, are in the range of 3.5-3.6 eV.

Optimising conditions for the growth of nanocrystalline ZnS thin films from acidic chemical baths

“…It has applications in photonic crystal sensors [1], heterojunction diodes [2], thin film photovoltaic cells [3][4][5][6][7], optical filters [8], light emitting diodes [9] and anti-reflection coatings [10]. Several methods have been employed to synthesize thin films including spray pyrolysis [11,12], solvothermal synthesis [13,14], sol-gel [2], successive ionic layer adsorption and reaction (SILAR) [15], pulsed laser deposition [16], close-space sublimation [17], metal-organic chemical vapor deposition (MOCVD), photo-assisted MOCVD [18], RF-mganetron sputtering [19,20], electrodeposition [21,22], thermal evaporation [23], aerosol assisted chemical vapor deposition (AACVD) [24,25], chemical bath deposition (CBD) [26][27][28][29][30][31][32][33][34] and film casting method [35,36]. Among these, CBD is potentially a simple, low temperature and cost effective method to high quality thin films.…”

Effects of Al content on physical properties of ZnS thin films prepared by chemical bath deposition

“…It has potential applications in optoelectronic devices [1] such as IR windows, photocatalytic degradation, bio-medical imaging and dilute magnetic semiconductors as [2,3], their wide-band-gap of 3.7 eV [4] could decrease the window absorption losses and improve the short-circuit current of the cells. To fabricate high quality ZnS thin films, various growth techniques have been used such as sol-gel [5], radio frequency magnetron sputtering [6], molecular beam epitaxy [7], spray pyrolysis [8], chemical vapor deposition [9], reverse micelle method [10], wet chemical route [11], microwave heating technique [12], hydrothermal technique [13] and chemical bath deposition (CBD) [14].…”

Effect of Zn:S molar ratio in solution on the properties of ZnS thin films and the formation of ZnS nanorods by spray pyrolysis

“…For instance, wurtzite ZnS with preferred orientation along (002) plane have good lattice matching to (112) plane of CuInS 2 for fabrication of a suitable lattice matched CuInS 2 /ZnS heterojunction in solar cell . The formation of ZnS with wurtzite structure is recorded very recently for ZnS thin films produced by spray pyrolysis at 330 °C using thioacetamide instead of thiocarbamide as sulfur source . ZnS films with wurtzite structure were prepared at 450 °C using ALD technique and by electrostatic‐assisted aerosol jet deposition close to 500 °C .…”