Structural, morphological and optical properties of annealed ZnS thin films deposited by spray technique

Abstract

ZnS thin films were deposited on glass slides by spray pyrolysis technique. The starting solution is a mixture of zinc chloride and thiourea. The substrate temperature was fixed at 350°C. The films were then annealed in the temperature range 300-450°C. Their thickness lies between 560 and 680 nm. We investigate the effect of this annealing on ZnS structural, morphological and optical properties. XRD analysis indicates that ZnS films have a nanocrystalline hexagonal structure with (002) preferential orientation. The grain size increases from 7 to 22 nm with annealing temperature. AFM images indicate a better crystalline phase for the films annealed at 450°C. The films show homogeneous, uniform distribution and surface roughness varying from 5 to 50 nm. The ZnS films exhibit transparency over 60-85 % in the visible and infrared region. The refractive index lies in the range 1.95-2.20. The band gap energy decreases from 3.76 to 2.65 eV for direct transitions. All results have been discussed in terms of annealing temperature. Furthermore, a ZnS/Si heterojunction was also fabricated by depositing n-type ZnS film on p-type Si substrate using spray method. The performance of the heterojunction was reported.

Dielectric and electrical properties of annealed ZnS thin films. The appearance of the OLPT conduction mechanism in chalcogenides

“…3. 23 We observed from these images the continuous growth of the layers. It can be seen that by increasing the annealing temperature the grain size and the roughness change.…”

“…Fig. 2 shows the XRD patterns of ZnS samples deposited by spray pyrolysis technique and annealed at different temperatures during 2 h. 23 The diffractograms show clearly that the as- 9550 | RSC Adv., 2020, 10, 9549 -9562 This journal is © The Royal Society of Chemistry 2020 deposited and annealed lms with temperature T a < 673 K have an amorphous structure. While the lms annealed at T a $ 673 K are partially transformed into a polycrystalline structure corresponding to hexagonal wurtzite phase of ZnS, characterized by preferred orientation (002).…”

Structural characteristics of a non-polar ZnS layer on a ZnO buffer layer formed on a sapphire substrate by mist chemical vapor deposition

“…Mist chemical vapor deposition (mist-CVD), which is similar to spray pyrolysis deposition, [1][2][3][4] uses a simple inexpensive system operated under atmospheric pressure. Therefore, much attention has been paid to mist-CVD as a low-cost deposition method.…”

Nanocrystalline and monophasic thin films of metal chalcogenide (FeS, ZnS) and oxide (ZnO) by chemical bath deposition (CBD)

“…Nanostructures of metal chalcogenides, especially, FeS, ZnS, and ZnO are the most important among all the sulfides and oxides . There are several physical and chemical techniques reported to date for the deposition of nanostructured thin films on a variety of substrates including thermal evaporation , electro‐deposition , hydrothermal method , sputtering , chemical spray‐pyrolysis , chemical bath deposition (CBD) , and aerosol assisted chemical vapor deposition (AACVD) . Simple and cost effective nature of the CBD makes it the most attractive method of deposition among the techniques mentioned above.…”