Patent ID: 7687871

Claim:
A photo-detector with a reduced dark current, comprising: a photo absorbing layer comprising a doped semiconductor exhibiting a valence band energy and a conducting band energy during operation of the photo-detector; a barrier layer comprising an undoped semiconductor, the barrier layer having a band energy gap and associated conduction and valence band energies, a first side of said barrier layer adjacent a first side of said photo absorbing layer; and a contact layer comprising a doped semiconductor exhibiting a valence band energy and a conducting band energy during operation of the photo-detector, said contact layer being adjacent a second side of said barrier layer opposing said first side; wherein the relationship between the photo absorbing layer and contact layer valence and conduction band energies and the barrier layer conduction and valance band energies facilitates minority carrier current flow while inhibiting majority carrier current flow between the contact and photo absorbing layers.