Effects of substrate temperature on absorption edge and photocurrent in evaporated amorphous SnS₂films

Abstract

The optical gap Eo and photocurrent peak Ep were investigated in amorphous SnS2 films evaporated onto glass substrates kept at a temperature from 294 to 609 K. For substrate temperatures up to 343 K, the film grew into an amorphous state with Eo=1.05+or-0.1 eV and Ep=2.1+or-0.05 eV. With increasing temperature, Eo increased markedly to 1.93 eV, while Ep decreased to 1.50 eV. By considering the results of radial distribution function obtained from the analysis of X-ray diffraction, the increase of Eo was explained in terms of a transition from an amorphous to a polycrystalline state. The substrate temperature dependence of the density of states was discussed including the result of two-step activation processes of electrical conductivity.

Structural and electrical properties of SnS2 thin films

“…In contrast to our results, in [39] wo activation energies were found: 0.20 eV in the temperature range of 300e365 K and 0.47 eV in the range of 365e400 K. In the paper [22], the two-step activation process was also observed. The activation energy of the donors was 0.26 eV below 242 K and 0.47 eV above 242 K.…”

“…As follows from Table 2, in SnS 2 films deposited at substrate temperatures of 473, 623, 673, and 723 K, the activation energies of donor centres are 0.25 and 0.26 eV. The same energies of the trap levels are observed in SnS 2 films obtained by vacuum thermal evaporation [22] and spray pyrolysis methods [14].…”

“…The advantages of SnS 2 are that it is non-toxic and its constituent elements (Sn and S) are cheap and Earthabundant. Tin disulfide thin films can be obtained using the following methods: ionic layer adsorption and reaction (SILAR) [18], spray pyrolysis [14,19e21], thermal vacuum evaporation [13,22], plasma-enhanced chemical vapour deposition (PECVD) [15], and dip coating [23]. Each of the methods of obtaining SnS 2 thin films has its advantages and disadvantages.…”

“…The values of conductivity of the SnS 2 films determined in the ohmic region (low-voltage region) of the IeV curves are shown in Table 2. As can be seen from [22,64] where SnS 2 films were deposited by thermal vacuum evaporation, the conductivity of the samples …”

Influence of tin precursor concentration on physical properties of nebulized spray deposited tin disulfide thin films

“…Thin films of SnS 2 were fabricated by various techniques like close-spaced sublimation [11], sulphurization of metallic precursors [12], atmospheric pressure chemical vapor deposition [13], chemical vapor transport [14], chemical deposition [15], vacuum evaporation [16,17], dip coating [18,19], solvothermal process [20], chemical spray pyrolysis [21,22] and each method has its own characteristic advantages and drawbacks in producing homogeneous and defect-free thin film. Among them, nebulized spray pyrolysis method is principal to prepare tin disulfide thin film, which is a low-cost method that can be used to coat uniform deposition on large surface area [23] with less solution wastage.…”