Abstract: A photodetector sensitive to ultraviolet wavelengths is capable of single photon sensitivity at room temperatures and video frame rates. It includes (a) a compound semiconductor photodiode, biased below its avalanche breakdown threshold, comprising III-V elemental components and having a bandgap with transition energy higher than the energy of visible photons; and (b) a high input impedance MOS interface circuit, arranged to receive a signal from the photodiode junction and to amplify said signal. Preferably, the photodiode junction is integrated in a first microstructure on a first substrate, and its interface circuit in a second microstructure on a second substrate. Both microstructures are then joined in a laminar, sandwich-like structure and communicate via electrically conducting contacts.

Abstract: A photodetector sensitive to visible and shorter wavelengths is capable of single photon sensitivity at room temperatures and video frame rates. It includes (a) a compound semiconductor photodiode, biased below its avalanche breakdown threshold, comprising III-V elemental components and having a bandgap with transition energy higher than the energy of infrared photons; and (b) a high trans-impedance interface circuit, arranged to receive a signal from the photodiode junction and to amplify said signal. Preferably, the photodiode junction is integrated in a first microstructure on a first substrate, and its interface circuit in a second microstructure on a second substrate. Both microstructures are then joined in a laminar, sandwich-like structure and communicate via electrically conducting contacts.