Modulation of structural properties of Sn doped ZnO for UV photoconductors

Sn doped ZnO thin films are synthesized in order to introduce excess charge carriers depending on various doping densities which modifies the surface, particle size and planar orientation of ZnO crystals. From the view of change in optical properties it is observed that with increasing Sn content, the increase in bandgap takes place which results into improved photo response as compared to pure ZnO. A highly-textured orientation in (002) direction has been observed with the relative increase in lattice parameters. Depending on Sn doping, photoconductor performance has been examined and an optimum Sn wt.% doping level is investigated to achieve maximum photo response in terms of sensitivity, ON/OFF ratio, spectral responsivity and detectivity. The maximum ON/OFF ratio and sensitivity are obtained to be 1.2×10⁵ and 1.0×10⁵ for 7 wt.% Sn doped ZnO sample. Similarly, the highest detectivity and spectral responsivity is obtained to be 1.7×10¹⁰ Jones and 1.56 A/W for 7 wt.% Sn-ZnO metal-semiconductor-metal photoconductor respectively.