EFFECT OF DEPOSITION PARAMETERS ON THE COMPOSITIONAL AND OPTICAL PROPERTIES OF Cu2SnS3 THIN FILMS PREPARED BY CHEMICAL BATH DEPOSITION

We investigated properties of Cu2SnS3 thin films prepared on glass substrates by chemical bath deposition. The effect on elemental composition and optical properties of deposition parameters, such as substrate temperature (T-s = 313 K, 323 K, 333 K and 343 K) and pH value of the chemical bath (1.0, 1.5 and 2.0), while using fixed deposition time of 80 minutes are reported. The composition, thickness and optical properties of the thin films were investigated using Rutherford backscattering spectrometry and UV-vis spectroscopy, respectively. The thicknesses of the prepared films fluctuated with the pH; however the temperature has not clear effect on the thickness. The compositional analysis showed that most of the samples were Cu rich and S poor with respect to stoichiometric Cu2SnS3. The films prepared at T-s = 343 K exhibited real phase composition in the range of 56-72%, depending on the solution pH. The optical energy direct transition band gap of the films ranged from 2.48 to 2.58 eV, depending on the deposition parameters. Thin film deposited at 343 K and pH = 2 showed the best optical properties, which makes it a suitable candidate for the fabrication of photovoltaic devices.