High Detection Sensitivity of Ultraviolet 4H-SiC Avalanche Photodiodes

Abstract

We report 4H-SiC p-i-n avalanche photodiodes (APDs) with very low dark current. When biased for a photocurrent gain M of 1000, a 100-mum-diameter device exhibits dark current of 5 pA (63 nA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), corresponding to primary multiplied dark current of 5 fA (63 pA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). The peak responsivity at unity gain is 93 mA/W (external quantum efficiency = 41%) at lambda = 280 nm. The excess noise factor corresponds to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> = 0.1. Detection of several tens of femtowatts of ultraviolet light is reported.