Vertical geometry ultraviolet photodetectors with high photosensitivity based on nanocrystalline TiO_2 films

摘要

Porous and dense nanocrystalline TiC>2 films grown on F:SnO substrates used in vertical geometry ultraviolet photodetectors are investigated. Compared with a detector with a dense nanocrystalline TiO_2 film (D-detec-tor), a detector with a porous nanocrystalline TiO_2 film (P-detector) exhibits one order of magnitude higher responsivity due to a light scattering effect. In addition, the vertical geometry detectors show a fast response time. The rise time and decay time of the P-detector and D-detector are 19 and 136 ns, and 14 and 100 ns, respectively, which are six orders of magnitude faster than those of lateral geometry detectors based on dense nanocrystalline TiO_2 films. It is a result of a decreased mobility fluctuation.