InGaAs/InAlAs avalanche photodiode with undepleted absorber

We report an avalanche photodiode with an undepleted p-type InGaAs absorption region and a thin InAlAs multiplication layer. The motivation for utilizing an undepleted absorption layer, which is similar to that in the unitraveling carrier photodiode, is to reduce the dark current. A dark current below 1 nA at a gain of 10 and a gain–bandwidth product of 160 GHz are demonstrated.