Qinetiq Limited

The Secretary of State for Defence in Her Britannic Majesty's Government

The Secretary of State for Defence

The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland

Neil Thomson Gordon

Charles Thomas Elliott

Timothy Ashley

Ralph S Hall

Anthony M White

Jean Giess

Janet E Hails

John W Cairns

Andrew Graham

Louise Buckle

David J Hall

Timothy Jonathan Phillips

Kevin Michael Brunson

Graham J Pryce

Colin John Hollier

Michael J Uren

Andrew J Wright

Ian Charles Carmichael

Charles Thomas Elliot

David George Gleaves

Ralph Stephenson Hall

Carl J Anthony

Ralph Stephen Hall

A method of manufacture of cadmium mercury telluride (CMT) is disclosed. The method involves growing one or more buffer layers on a substrate by molecular beam epitaxy (MBE). Subsequently at least one layer of cadmium mercury telluride, Hg1-xCdxTe where x is between 0 and 1 inclusive, is grown by metal organic vapour phase epitaxy (MOVPE). The use of MBE to grow buffer layers allows a range of substrates to be used for CMT growth. The MBE buffer layers provide the correct orientation for later MOVPE growth of CMT and also prevent chemical contamination of the CMT and attack of the substrate during MOVPE. The method also allows for device processing of the CMT layers to be performed with further MOVPE growth of crystalline CMT layers and/or passivation layers. The invention also relates to new devices formed by the method.

Manufacture of cadmium mercury telluride

This invention relates to the manufacture of Cadmium Mercury Telluride (CMT) on patterned silicon, especially to growth of CMT on silicon substrates bearing integrated circuitry. The method of the invention involves growing CMT in selected growth windows on the silicon substrate by first growing one or more buffer layers by MBE and then growing the CMT by MOVPE. The growth windows may be defined by masking the area outside of the growth windows. Growth within the growth windows is crystalline whereas any growth outside the growth windows is polycrystalline and can be removed by etching. The invention offers a method of growing CMT structures directly on integrated circuits removing the need for hybridisation.

Manufacture of cadmium mercury telluride on patterned silicon

A communications system incorporates a transmitter a receiver. The transmitter includes an infrared light emitting diode (LED). The LED output is positive or negative luminescence, i.e. above or below an equilibrium background intensity level respectively, according to the polarity of its bias signal. The receiver contains a lens to focus light from the LED onto a diode detector, from which signals pass to an amplifier, decoder and printer. Output signals from the LED have an average intensity equal to the equilibrium background intensity level and a frequency greater than 100 Hz or byte rate greater than 100 bytes/sec. They are not discernible by conventional thermal infrared imagers with frame rates of 50 Hz or less because integration in such an imager renders them indistinguishable from background.

Communications system

A multi-layer semiconductor diode having a layer of wide bandgap material located between the active layer and a first contact zone, where the active layer and additional wide bandgap layer are of one dopant type, and the first contact zone is of the opposite dopant type. A specific embodiment of the invention comprises a stack formed from a first contact zone () of p-type material, a lightly doped p-type active layer (), an additionallayer () and a second contact zone () of n-type material. The diode may be used as an infrared detector or a negative luminescent source.

Semiconductor diode device

An infra-red detector ( ) comprises a detector region ( ) and a collector region separated by a barrier region. Operation of these regions is controlled by potentials applied to respective gate electrodes ( ), insulated from the detector, barrier and collector regions by an insulating oxide layer ( ). The detector, barrier, and collector regions may be arranged on a silicon substrate ( ). In operation, photo-excited electrons are generated in the detector region and these cross the barrier region for readout from the collector region.

Infra-red detector

A noise reduced photon detector incorporates an array ( ) of semiconductor diode detector elements ( ). Each element ( ) has an extrinsic active layer ( ) sandwiched between two layers ( ) of wider bandgap and mutually opposite conductivity type. These layers are in turn sandwiched between two further layers ( ) of wider bandgap than the active layer ( ) and of higher doping than the other layers ( ). A mirror ( ) extends round much the array ( ) and isolates each element ( ) from photons emitted by other elements ( ). In operation the elements ( ) are reverse biased and exhibit negative luminescence which reduces their photon emission. These two effects reduce unwanted photon generation and absorption, and consequently photon noise is also reduced.

Noise reduced photon detector

A thermal imaging system (,) which is accoupled and by scanning recreates a thermal image by superimposing measured variations in infrared emission from a scene (,) onto a reference level supplied by a light emitting diode (,). The diode (,) is both a positive and negative luminescent emitter. Emitted flux is current controlled to be equivalent to black body radiation at a range of temperatures which may be colder or hotter than ambient. A signal generated with the system (,) switches between scene and diode observation is a measure of the difference between the mean scene temperature and the diode effective temperature. In response to this digital, control means adjust the bias current through the diode (,) in order to reduce the temperature difference. The reference temperature converges towards the mean scene temperature as this process is repeated. Absolute temperature is thus restored and some image defects removed.

Thermal imaging system

Thermal sensing system having a fast response calibration device

Infrared optical system

Dynamic infrared scene projector

Growing community of inventors

Malvern, United Kingdom

Neil Thomson Gordon