High-Detectivity and High-Single-Photon-Detection-Efficiency 4H-SiC Avalanche Photodiodes

We report large-area, 250-mum-diameter, 4H-SiC avalanche photodiodes with low dark current and high gain. At room temperature, the dark current density is 59.5 nA/cm
²
at a gain of 1000. An external quantum efficiency of 48% at 280 nm is achieved at unity gain with a recessed-window structure. The differential resistance of the recessed-window device at zero bias is estimated to be 6times10
¹⁴
Omega. As a result of high external quantum efficiency, large area, and large differential resistance, a record high specific detectivity of 4.1times10
¹⁴
cmHz
^1/2
W
^-1
, has been achieved. In Geiger mode operation, high single photon detection efficiency of 30% with dark count probability of 8times10
^-4
is reported.