Quantum well infrared photodetector
Encyclopedia
A quantum well infrared photodetector (QWIP), is an infrared
photodetector
made from semiconductor
materials which contain one or more quantum well
s. These can be integrated together with electronics and optics
to make infrared cameras for thermography
. A very common well material is gallium arsenide, used with barrier material aluminium gallium arsenide
. There are several companies world-wide manufacturing infrared systems which use QWIPs. It is also considered a game changing technology in the field of visual range air to air missiles, where it can detect objects which are well outside the visual range of the pilot.
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
photodetector
Photodetector
Photosensors or photodetectors are sensors of light or other electromagnetic energy. There are several varieties:*Active pixel sensors are image sensors consisting of an integrated circuit that contains an array of pixel sensors, each pixel containing a both a light sensor and an active amplifier...
made from semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
materials which contain one or more quantum well
Quantum well
A quantum well is a potential well with only discrete energy values.One technology to create quantization is to confine particles, which were originally free to move in three dimensions, to two dimensions, forcing them to occupy a planar region...
s. These can be integrated together with electronics and optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
to make infrared cameras for thermography
Thermography
Infrared thermography, thermal imaging, and thermal video are examples of infrared imaging science. Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum and produce images of that radiation, called thermograms...
. A very common well material is gallium arsenide, used with barrier material aluminium gallium arsenide
Aluminium gallium arsenide
Aluminium gallium arsenide is a semiconductor material with very nearly the same lattice constant as GaAs, but a larger bandgap. The x in the formula above is a number between 0 and 1 - this indicates an arbitrary alloy between GaAs and AlAs.The bandgap varies between 1.42 eV and 2.16 eV...
. There are several companies world-wide manufacturing infrared systems which use QWIPs. It is also considered a game changing technology in the field of visual range air to air missiles, where it can detect objects which are well outside the visual range of the pilot.