High responsivity 4H-SiC Schottky UV photodiodes based on the pinch-off surface effect

In this letter, high responsivity 4H-SiC vertical Schottky UV photodiodes based on the pinch-off surface effect, obtained by means of self-aligned Ni2Si interdigit contacts, are demonstrated. The diode area was 1 mm(2), with a 37% directly exposed to the radiation. The dark current was about 200 pA at -50 V. Under a 256 nm UV illumination, a current increase of more than two orders of magnitude is observed, resulting in a 78% internal quantum efficiency. The vertical photodiodes showed an ultraviolet-visible rejection ratio > 7x10(3) and a responsivity a factor of about 1.8 higher than a conventional planar metal-semiconductor-metal structure.