Observation of giant photocurrent gain in highly doped (In,Ga)N∕GaN multiple-quantum-well-based photodiodes

The authors report on the observation of a giant photocurrent gain (>106) in highly doped (In,Ga)N∕GaN multiple-quantum-well-based photodiodes, which decreases with temperature. This large photocurrent gain appears at low forward bias and strongly depends on the current transport mechanism. Results of capacitance-voltage measurements show that the photocurrent gain is related to the screening of the built-in electric field by charge accumulation. The role of the (Al,Ga)N electron blocking layer in current transport has been studied by comparing samples nominally identical except for the existence of this layer.