Impact of substrate -target distance on the hemispherical expansion plume generated by the deposit of SnSe nanoparticle thin films

Abstract

The pulsed laser deposition technique utilised to deposit SnSe thin films on quartz substrates utilises Nd:YAG laser at the temperature of 573 ​K with different substrate–target distances (Ds-t) of 2, 2.5, 3 and 3.5 ​cm. X-ray diffraction of the thin films revealed an orthorhombic phase with a polycrystalline structure. Crystallite size decreased when Ds-t increased. Field emission scanning electron microscopy showed the film morphology and revealed the formation of spherical and nanorod structures with increasing Ds-t. The energy band gap calculated from transmittance data increased in the range of 1.71–3.65 ​eV with increasing Ds-t. The absorption coefficient, refractive index, loss factor (loss tangent), extinction coefficient and optical conductivity were affected by Ds-t variation.