Effect of deposition temperature on structural, optical and electrical properties of nanocrystalline SnSe thin films

SnSe thin films have been prepared by chemical bath deposition method at different substrate temperature. The influence of deposition temperature on structural, optical and electrical properties of polycrystalline SnSe films have been investigated using X-ray diffraction, optical absorbance and conductivity measurements. The X-ray diffraction study reveals the orthorhombic structure of the SnSe films oriented along the (111) direction. The structural parameters such as lattice spacing, crystallite size, strain, number of crystallites per unit area and dislocation density have been evaluated. Optical absorbance measurement indicates the existence of direct allowed band gap in the range 1.50–1.91 eV. The dark conductivity (σd) and photoconductivity (σph) measurement in the temperature range (278–385 K), indicates that the conduction in these materials is through an activation process having one activation energy. σd and σph values decrease with the decrease of crystallite size. The value of photosensitivity, carrier life time and trap depth have also been calculated.