Low Operating Voltage and Small Gain Slope of InGaAs APDs With p-Type Multiplication Layer

We reported separate absorption and multiplication InAlAs/InGaAs avalanche photodiodes with a p-type multiplication layer. Wedge-shaped electric field profiles with different gradients and peak intensities confined in a thin InAlAs avalanche layer were realized. These devices showed optimum operating gains up to 40 in linear mode with low operating voltages <;20 V, small gain slopes, and high-gain uniformity. Moreover, a reduced breakdown voltage temperature coefficient <;6 mV/K in the temperature range of 200-350 K was observed, whereas the dark current showed a noticeable increase. Those multiplication performances are attributed to the modified electric field profiles and are ideally suitable for focal plane array imaging applications.