Low dark current photodetector

A low dark current metal-semiconductor-metal photodetector has an active region for receiving photons and generating charge carriers in the form of holes and electrons in response to the photons and an isolation region for allowing electrical coupling to occur without increasing the dark current. The photodetector is a III-V ternary semiconductor having its active region defined by a via through a dielectric layer. A pair of electrodes has contact portions extending into contact with the active region and terminating on the isolation region. One electrode of the pair provides a high Schottky barrier to holes. The other electrode provides a high Schottky barrier for electrons