Low dark current, resonant cavity-enhanced infrared photodetectors

摘要

A resonant cavity-enhanced infrared photodetector has an absorber layer disposed between a first transparent layer and a second transparent layer within an optical cavity. The first transparent layer and the second transparent layer have a bandgap which is larger by at least 0.1 eV compared to the absorber layer. Since the bandgaps of the first and second layer are increased relative to the bandgap of the absorber layer, generation of dark current is limited to the absorber layer. The band profiles of the layers had been designed in order to avoid carrier trapping. In one embodiment, the conduction and valence band offsets are configured to allow unimpeded flow of photogenerated charge carriers away from the absorber layer. The photodetector may be a photoconductor, or a photodiode having n-type and p-type layers. In some embodiments, an interface between the absorber layer and a transparent layer is compositionally graded. In other embodiments, one of a conduction band and a valence band of the absorber layer is aligned with an opposite band of a transparent layer so that a photogenerated charge carrier can tunnel from one band of the absorber layer into the opposite band of the transparent layer.