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 (285nm to 360nm) with higher than 100A/W photoresponsivity, and a peak photoresponsivity of 738A/W at 320nm. The visible-blind rejection ratio, defined as the maximum responsivity divided by the responsivity at 400nm, has a maximum value of about 2500 at 93.9V reverse bias. The APD photoresponse speed is studied and a fall time of 4.0ns is measured.