Tuning of photosensitivity and optical parameters of ZnO based photodetectors by co-Sn and Ti doping

In this study it was shown that co-doping of zinc oxide (ZnO) thin films with tin (Sn) and titanium (Ti), can significantly increase photosensitivity of metal-semiconductor-metal (MSM) type ZnO based photodetectors. Doping of ZnO thin films was carried out by non-vacuum sol-gel process. The 0.5% Sn and 1% Ti doped thin films show highest photosensitivity under 365 nm light illumination. The photosensitivity increased from 42 to 1552 with the addition of Sn and Ti. Furthermore, the decay time of pristine (undoped) photodetector decreased from 31.2 s to 5.4 s by tuning doping concentration to 1% Sn and 1% Ti. These results indicate that co-doping of ZnO thin films with Ti and Sn can enhance on/off current ratio and decay time parameter of the photodetector. Furthermore, the absorption coefficient, optical conductivity refractive index, skin depth, extinction coefficient and dielectric constants of samples strongly change with doping of ZnO thin films, which can be useful for optoelectronic applications.

Automated summary

This study shows that co-doping ZnO thin films with Sn and Ti can greatly enhance the photosensitivity and decay time of photodetectors. Co-doping also alters various optical properties of ZnO thin films, which are beneficial for optoelectronic applications.