Demonstration of high performance visible-blind 4H-SiC avalanche photodiodes

4H-SiC visible-blind reach-through avalanche photodiodes (RAPDs) are designed and fabricated with mesa edge termination and thermal oxide passivation techniques. The devices show a `hard' avalanche breakdown with a positive temperature coefficient, a wide spectral range (285 nm to 360 nm) with higher than 100 A/W photoresponsivity, and a peak photoresponsivity of 738 A/W at 320 nm. The visible-blind rejection ratio, defined as the maximum responsivity divided by the responsivity at 400 nm, has a maximum value of about 2500 at 93.9 V reverse bias. The APD photoresponse speed is studied and a fall time of 4.0 ns is measured.