LOW-VOLTAGE HIGH-GAIN RESONANT-CAVITY AVALANCHE PHOTODIODE

For p-i-n photodiodes and avalanche photodiodes in the low-gain regime, there is a performance tradeoff between the transit-time contribution to the bandwidth and the quantum efficiency. We demonstrate a new photodetector structure that alleviates limitations imposed by this tradeoff. This structure utilizes a thin (almost-equal-to 900 angstrom), depleted absorbing layer to reduce the transit time and achieve avalanche gain at low bias voltage (V(b) almost-equal-to 9 V). The external quantum efficiency has been enhanced (eta-e > 49%) by incorporating the structure into a resonant cavity.