Ultraviolet photodetector with high internal gain enhanced by TiO2/SrTiO3 heterojunction

In this letter, TiO2 nanocrystalline film was prepared on SrTiO3 (001) substrate to form an n-n heterojunction active layer. Interdigitated Au electrodes were deposited on the top of TiO2 film to fabricate modified HMSM (heterojunction metal-semiconductor-metal) ultraviolet photodetector. At 10 V bias, the dark current of the detector was only 0.2 nA and the responsivity was 46.1 A/W at 260 nm. The rise and fall times of the device were 3.5 ms and 1.4 s, respectively. The TiO2/SrTiO3 heterojunction contributed a lot to the high responsivity and reduced the fall time, which improved the device performance effectively. These results demonstrate the excellent application of TiO2/SrTiO3 heterojunction in fabricating high performance UV photodetectors. (c) 2012 Optical Society of America