Photovoltaic Three-Dimensional Diamond UV Photodetector With Low Dark Current and Fast Response Speed Fabricated by Bottom-Up Method

Fabrication of a low-dark-current and high-response-speed three-dimensional diamond UV photodetector using the bottom-up method is demonstrated. The photovoltaic detector exhibits typical rectifier I-V characteristics. The dark current is 14.2 pA under a reverse bias of 10 V, and it is five-orders-of-magnitude lower than that of photoconductive detectors. Transient response measurement indicates that the decay time of the photovoltaic detector is about 590 ms and the persistent photoconductivity phenomenon is weak. This remarkable reduction of the dark current and persistent photoconductivity can be attributed to the Schottky barrier formation between W and oxygen-terminated diamond. The photovoltaic detector also demonstrates a larger deep UV-to-visible rejection ratio than photoconductive detector.