High-performance visible blind ultraviolet photodetector based on KTaO3 single crystal

We report a visible-blind ultraviolet photoconductive detector with interdigitated electrodes based on KTaO3 (KTO) single crystals. Both the steady spectral responses and the transient photovoltaic measurements clearly exhibit a cutoff wavelength at 344 nm (similar to 3.6 eV), in accordance with the bandgap of KTO. The KTO photo-detectors show a low dark current similar to 1.5 pA at 20 V, and a high UV-to-visible rejection ratio with 3 orders of magnitude at room temperature. The quantum efficiency is 37.49% under 20 V bias, and the detectivity D* of 3.85 x 1012 cm . Hz(0.5)/W, which is comparable to that of silicon photodetectors in the UV region. The rise time of photoelectric response is similar to 260 ps, indicating an ultrafast photoelectric response characteristic. The present work offers appealing prospects for the application of KTO materials in high-performance visible blind ultraviolet photodetectors. (C) 2016 Optical Society of America