High-performance violet phosphorus photodetectors with van der Waals-assisted contacts

Black phosphorus (BP) as a narrow-bandgap two-dimensional semiconductor material has been extensively studied. And the allotrope violet phosphorus (VP) exhibits wide bandgap properties extending the application in the visible light band. However, due to the Schottky barrier of metal/semiconductor contacts (M/S), further device application of VP is limited. Here, VP-based photodetectors with van der Waals-assisted contact were demonstrated, achieving quasi-Ohmic M/S contacts. The output characteristics in dark conditions show ultralow current at the pA level. And the device exhibits a high current on-off ratio of 10 5 and a fast response speed of 8.4 ms. Furthermore, we constructed the first allotropic photodetector based on BP and VP heterojunction. The device maintains ultralow dark current (∼ pA) while exhibiting faster carrier transport, with 945 µs response time and polarization detection capability. These results offer an effective way to study the optoelectronic properties of VP and promote the study of allotropic heterojunction devices.