4H–SiC ultraviolet avalanche photodetectors with low breakdown voltage and high gain

The separate absorption and multiplication (SAM) 4H–SiC ultraviolet (UV) avalanche photodetectors (APDs) have been designed, fabricated and characterized. A gain higher than 1.8 × 104 was achieved at 90% breakdown voltage of ∼55 V. At 0 V, the peak absolute responsivity was estimated to be larger than 0.078 A/W at 270 nm, corresponding to a peak external quantum efficiency of over 35.8%. The long-wavelength cutoff was about 380 nm. In addition, the UV-to-visible rejection ratio of around three orders of magnitude was extracted from the spectra response. When the reverse bias was larger than 35 V, the spectral responsivity enhanced distinctly. At the reverse bias of 42 V, the peak responsivity increased to 0.203 A/W at 270 nm, corresponding to a maximum external quantum efficiency of ∼93%, which showed a distinct avalanche behavior. Furthermore, the ideality factor around 1.65 and the spectral detectivity about 3.1 × 1013 cm Hz1/2 W−1 were estimated. In conclusion, the 4H–SiC APD have excellent performance for UV detection.