Abstract: An IR photodetector including an IR semiconductor detector with conductive layers on opposite, parallel surfaces. A semiconductor substrate supports the semiconductor IR detector. A circuit is connected across the semiconductor IR detector to provide a bias voltage and for measuring current flow through the semiconductor IR detector. The semiconductor IR detector has a lattice structure made up of a series of potential wells separated by relatively wide potential barriers such that each well has two confined energy levels. A thin spike barrier is placed in the center of alternate potential wells to tailor the absorption characteristics of the semiconductor IR detector. Multicolor operation is achieved by selecting the appropriate well widths for a first group of potential wells and by placing thin spike barriers in a second group of potential wells that are alternately placed between the wells of the first group.

Abstract: An infrared hot-electron transistor comprising a doped multiple quantum well structure as an infrared radiation sensitive unit, and an electron energy filter as a dark current reduction unit. Infrared radiation incident on the device gives rise to intersubband absorption. After having absorbed an infrared photon, each photoelectron is one photon energy higher in energy than that of the dark electron, and hence can be separated by an electron energy filter. The transistor consists of three terminals, each of them has an indispensable function. The emitter supplies electrons, the collector collects photoelectrons, and the base provides drainage to the unwanted dark electrons.

Abstract: A multicolor infrared detection device comprising a number of doped quantum ell structural units. Each unit consists of a thick well and a thin well separated by a thin barrier. This arrangement produces strong coupling. Infrared radiation incident on the device gives rise to intersubband absorption. For each transition a photosignal results which allows the detection of a plurality of incident frequencies.

Abstract: A narrow-bandwidth, high-speed infrared radiation detector is based on tunneling of photo-excited electrons out of quantum wells. Infrared radiation incident on a superlattice of doped quantum wells gives rise to intersubband resonance radiation which excites electrons from the ground state into an excited state. A photocurrent results from excited electrons tunneling out of quantum wells. Conveniently, Group III-V materials can be used in device manufacture. Preferably, quantum well potential barriers are shaped so as to facilitate resonant tunneling of photocurrents as compared with dark current. Preferred device operation is at elevated bias voltage, giving rise to enhancement of photocurrent by a quantum-well-avalanche effect.