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

Qinetiq Limited

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

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

Philips Electronic and Associated Industries Ltd.

Charles Thomas Elliott

Timothy Ashley

Anthony M White

Neil Thomson Gordon

Timothy Jonathan Phillips

Ralph S Hall

Anthony B Dean

Huw D Rees

Kevin Michael Brunson

Richard George Humphreys

Rex Watton

Colin R Whitehouse

Howard J Field

Carl J Anthony

Michael J Uren

David E Charlton

Raymond Brewitt-Taylor

Peter N Dennis

Ralph Stephen Hall

Anthony Brian Dean

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

The invention provides a Hall effect magnetic field sensor ( ) including carrier excluding or extracting means ( ) for reducing an intrinsic contribution to carrier concentration in the active region ( ) to provide for the sensor to be operative in an extrinsic saturated regime. This provides an advantage that magnetic field measurement sensitivity of the sensor ( ) can be made substantially insensitive to sensor temperature thereby improving measurement accuracy.

Magnetic field sensor including carrier excluding for reducing an instrinsic contribution to carrier concentration in the active region

A field effect transistor (FET) is of the type which employs base biasing to depress the intrinsic contribution to conduction and reduce leakage current. It incorporates four successive layers ( to ): a p InSb base layer ( ), a InAlSb barrier layer ( ), a &pgr; intrinsic layer ( ) and an insulating SiO layer ( ); p source and drain regions ( ) are implanted in the intrinsic layer ( ). The FET is an enhancement mode MISFET ( ) in which biasing establishes the FET channel in the intrinsic layer ( ). The insulating layer ( ) has a substantially flat surface supporting a gate contact ( ). This avoids or reduces departures from channel straightness caused by intrusion of a gate groove, and enables a high value of current gain cut-off frequency to be obtained. In FETs with layers that are not flat, departures from channel straightness should not be more than 50 nm in extent, preferably less than 5 nm.

High frequency field effect transistor with carrier extraction to reduce intrinsic conduction

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

Semiconductor device with low thermally generated leakage current

A thermal imaging device having both serial and parallel content is provided by a number of infra-red radiation detector strips supported side by side on an insulating substrate, each strip having a number of read-out regions. To allow connection from the side of the device to the innermost detector strips, conductors err end across outer strips. These conductors may extend over the strips and over insulating material therebetween. Alternatively the conductors may be in the form of conductive tracks embodied in a substrate of semiconductor material. The strips may be indented at the read-out regions to provide, with very close spacing, sufficient room for contact between the read-out regions and the conductive tracks. Preformed aluminium contact pads may be used between bridging links to the read-out regions and the conductive tracks the contact pads and preformed tracks being centered during preformation to ensure a good ohmic contact.

Thermal imaging devices

An infrared detector comprises a thin film of photo-responsive material on transparent dielectric material with an array of planar antennae adjacent to the film surface. The antennae are separate from ohmic contacts arranged to connect the film to an external circuit. The antennae concentrate radiation in fringe fields at antenna edges and extremities interacting with the photo-responsive material. The detectors may be photovoltaic or photoconductive. The antennae may be rectangular, bow-tie, cruciform, elliptic, circular or square, and are dimensioned for resonance (preferably half-wavelength resonance) at frequencies within the photo-responsive material absorption band. Half-wavelength resonant antennae are best matched by F/0.7 optics. The detector may be a reticulated array. The dielectric material may be formed as a lens.

Infrared detectors

Multiple heterostructure photodetector

A photodetector of semiconductor material includes a photosensitive region adjacent to a minority carrier extraction region arranged when biased to depress the photosensitive region minority carrier concentraction, and means for inhibiting injection of minority carriers to the photosensitive region. Depression of the minority carrier concentration produces low noise and high responsivity properties as obtained by cooling, but without the need for cooling equipment. The minority carrier extraction region may be a pn homo- or heterojunction. Minority carrier injection may be inhibited by a homo- or hetero-structure excluding contact to the photosensitive region, or alternatively by providing the photosensitive region with at least one subsidiary pn junction biasable to inhibit minority carrier flow. The photosensitive region may have an array of extraction regions spaed by less than a minority carrier diffusion length. The extraction regions may have separate outputs to provide respective pixels in a display.

Photodetector semiconductor which does not require extensive cooling

Between the spaced biasing electrodes of a thermal radiation imaging device A D.C. bias source is connected to cause the flow of a bias current in the device body which is preferably of n-type cadmium mercury telluride. The bias current supports an ambipolar drift of radiation-generated minority carriers (holes) in the opposite direction. The device is operated in a system in which the radiation pattern is scanned across the device body in the same direction and at the same rate as the ambipolar velocity. Instead of having a single read-out electrode, a more sophisticated system with better performance is obtained by distributing between the spaced biasing electrodes a plurality of read-out electrodes each of which forms a Schottky barrier or p-n junction with the body material.

Thermal radiation imaging devices and systems

Growing community of inventors

Malvern, United Kingdom

Charles Thomas Elliott