Characterization of a top‐illuminated p‐i‐n diode with an indium tin oxide contact

The characteristics of a new type of AlGaAs/GaAs p‐i‐n photodiode are reported. Indium tin oxide forms the contact to the upper AlGaAs layer and serves also as an antireflection coating. Our devices show very low dark currents (20–300 pA at 5 V reverse bias for devices of 20–200 μm diameter), high speed (full width at half maximum <60 ps), and high sensitivity (61% external quantum efficiency) at 1 V bias. A microwave analysis of the diode is presented.