Sol–gel preparation of Sn doped gallium oxide films for application in solar-blind ultraviolet photodetectors

Ga 2 O 3 is considered as a candidate for the preparation of solar-blind photodetectors due to its large direct band gap. Developing low-cost preparation methods of high-quality Ga 2 O 3 films is of importance for large-scale applications. In this work, we investigate the preparation of Sn doped β-Ga 2 O 3 films by using simple and cheap sol–gel method under ambient condition. It is found that Sn doping induces a growth mode transformation from \(\left( {\overline{2}01} \right)\) to \(\left( {\overline{3}11} \right)\) oriented texture on the c-plane sapphire substrates. With an optimal Sn proportion, high-quality β-Ga 2 O 3 films consisting of needle-like grains are observed. Compared with the undoped films, the Sn-doped films with needle-like grains obtained a low dark current of 0.76 nA, performed an on/off ratio as high as ~ 6000, responsivity, R of 164 mA/W and D* of 3.21 × 10 12 Jones at a bias voltage of 30 V in the configuration of metal–semiconductor–metal solar-blind deep ultraviolet detectors. This is the highest on/off ratio of Ga 2 O 3 solar-blind photodetectors fabricated by sol–gel method reported up to now and has the potential to be applied in practical use. Graphical abstract