An efficient MSM UV photodetector with an ultra-low dark current enhanced by a back to back TiO2/PbTiO3 PN heterojunction

A TiO2 MSM UV photodetector has been extensively researched and exhibits many good properties such as stability and a large ratio of light to dark current. However, it suffers from a high dark current and slow response and recovery. In this work, an MSM UV photodetector based on a TiO2/PbTiO3 heterojunction was fabricated by a sol-gel method. Spontaneous polarization of ferroelectric perovskite PbTiO3 can deplete carriers and accelerate the separation and transport of photo-generated carriers. The photodetector showed enhanced performances, including an ultra-low dark current (1.146 19 × 10−11 A), an improving ratio of light to dark current, as well as short response and recovery times (decreasing to 65 and 81 ms). These results indicate the potential in the combination of ferroelectric perovskite PbTiO3 with traditional wide bandgap semiconductor materials to fabricate high-performance UV photodetectors.