Large-area Visible-blind 4H-SiC Ultraviolet Avalanche Photodiode with High Gain and Low Bias Voltage

Based on the separate absorption and multiplication (SAM) structure, visible-blind 4H-SiC ultraviolet avalanche photodiodes (APDs) with large active area (400 μm diameter) were designed and fabricated in this work. The results show that high optical gain of 1.7×10⁶ and low bias voltage (i.e. low breakdown voltage) of 50.6 V are achieved at room temperature. Additionally, a maximum quantum efficiency of 30% is obtained at 270nm with the reverse bias voltage of 10 V, which can be further improved by optimizing device structures.