Solar-Blind 4H-SiC Single-Photon Avalanche Diode Operating in Geiger Mode

A solar blind 4H-SiC single photon avalanche diode (SPAD) with a sharp cutoff at a wavelength of 280 nm is reported. The SPAD with separate absorption and multiplication layers was designed for operation in Geiger mode. A thin film optical filter deposited on a sapphire window of the device package provided sensitivity in the wavelength range between 240 and 280 nm with a very high solar photon rejection ratio. An estimated dark current of 0.4 pA (0.75 nA/cm²) at a gain of 1000 was measured on a device with an effective mesa diameter of 260 mum. A single photon detection efficiency of 9.4% and a dark count probability of 4 times 10^-4 were demonstrated at a wavelength of 266 nm for the same device.