Patent ID: 7368762

Claim:
A heterojunction photodiode, comprising: a pn or Schottky-barrier junction formed in a first material region having a bandgap energy E g1 ; and a second material region having a bandgap energy E g2 which is less than E g1 positioned adjacent to said first material region, the material of said second material region characterized in that dark currents through said second material region are limited by fundamental Auger processes, said junction creating a depletion region in said first material region which expands towards said second material region in response to a reverse bias voltage such that the dark current flowing through said junction is reduced, said photodiode arranged such that said depletion region extends into said second material region when said reverse bias voltage is greater than a predetermined value; wherein said photodiode is arranged such that said second material region is thin enough such that it is fully depleted by said depletion region, thereby minimizing dark currents associated with fundamental Auger processes.