Structural, Optical, and Electro-Optical Properties of Thermally Evaporated Tin Sulphide Layers

Abstract

Thin films of tin sulphide (SnS) were deposited onto glass substrates using the thermal evaporation method. The substrate temperature, Ts was varied in the range, 280–360 °C, keeping other growth parameters constant and the effects on the chemical and physical properties of the layers deposited were investigated. The layers were observed to consist of densely packed grains, up to 9.5 µm in diameter, and X-ray diffraction studies showed the layers had a strong preferred (040) orientation. The energy band gap, determined from optical studies was found to be in the range 1.30–1.34 eV, while the optical absorption coefficient was found to be >104 cm-1 for photons with energies greater than the energy bandgap. The electrical resistivity of the films decreased with an increase of substrate temperature. Heterojunction devices were made using chemical bath deposited cadmium sulphide (CdS) as the window layer and the minority carrier diffusion length in the SnS measured to be 0.23 µm using spectral response studies.