High-performance 4H-SiC-based ultraviolet p-i-n photodetector

A high-performance 4H-SiC p-i-n photodetector for visible-blind ultraviolet (UV) applications has been designed and fabricated. The electrical and optical characteristics were measured at room temperature. The photodetector suffered from significant dark current of 2.5 pA/mm2 at reverse bias of 5 V, and the UV light photocurrent was larger than four orders of magnitude higher than the dark current. The built-in potential and the unintentional i-layer doping concentration were obtained from capacitance-voltage (C-V) measurements. The spectral peak responsivity of the detector reached 0.13 A/W at a wavelength of 270 nm, corresponding to a maximum external quantum efficiency of ∼61%. And the ratio of responsivity at 270 nm to that at 380 nm was >103. The characteristics imply that the photodetector has a great improved ultraviolet-visible rejection ratio which is needed for ultraviolet signal detection.