Martin Marietta Corporation

Robert W Yanka

Milton L Noble

Karl A Harris

Thomas H Myers, Ii

Gregory K Dudoff

Lee M Mohnkern

Richard J Williams

Thomas H Meyers, Iii

A dual band IR scanning focal plane assembly includes two linear detector arrays in a close spaced configuration monolithically integrated on a common substrate. A medium wave IR staggered element linear array is formed on the front (111)B face of a (111) crystallographically oriented CdZnTe substrate in an MCT layer deposited by the molecular beam epitaxial (MBE) process. A long wave IR staggered element linear array is formed on the back (111)A face of the substrate in an MCT layer deposited by the liquid phase epitaxial (LPE) process. The sets of odd and even rows of the LWIR array on the back face are contiguous, while the sets of odd and even rows of the MWIR array on the front face are close-spaced, the spacing being just wide enough to allow a clear optical path to the underlying linear LWIR array. The arrangement provides simplified spectral separation of the simultaneously readout MWIR and LWIR images.

Dual-band IR scanning focal plane assembly having two monolithically

A compact dual band IR focal plane assembly provides simultaneous, coincident two-dimensional image readout. It includes a MIS-CID MWIR detector array formed in an epitaxial layer grown by the MBE process on the (111B) front face of an IR transparent crystalline first substrate, the pixels thereof forming LWIR transparent windows, with opaque connections thereto lying in aisles framing the windows, and a PV diode LWIR detector array formed in an epitaxial layer grown by the LPE process on the (111A) back face of the substrate, the LWIR pixels being aligned with the transparent MWIR pixels. An MWIR MUX is provided on an IR transparent silicon second substrate arranged in front of the first substrate. The opaque switch portion of the MWIR MUX is arrayed with apertures and aisles in alignment with the windows and aisles of the MIS-CID array. An LWIR MUX is provided on a third substrate bonded to the LWIR detector array beyond the image paths, the MWIR and LWIR MUXes providing simultaneous, coincident image readout.

A-dual band IR sensor having two monolithically integrated staring

An improved x-ray detector in the form of a p-i-n CdTe homojunction device is disclosed. The intrinsic ('i') layer is of high resistivity CdTe, while the n- and p-doped CdTe layers are epitaxially grown in a photo-assisted process in a molecular beam epitaxial apparatus. The n-dopant is conveniently indium, with an indium metal contact. The 'i' layer is optionally epitaxially grown in a photo-assisted process. The p-dopant is preferably arsenic. A PAMBE formed mercury telluride contact layer enhances the ohmic contact to the p-layer, and a gold contact is provided to the contact layer. The use of the PAMBE technique facilitates high quality crystal growth and activation of the dopants. The resulting CdTe p-i-n homojunction device has a wide band gap (1.45 eV) essential to room temperature operation.

CDTE x-ray detector for use at room temperature

A typical source of cadmium and tellurium is as a by-product of copper mining. Although attempts are made to remove impurities such as copper prior to commercially supplying them for forming material like cadmium telluride, cadmium zinc telluride and cadmium telluride selenide for use as a substrate to support electronic circuitry, processing during formation of the circuitry causes the impurities from the substrate to segregate into the circuitry, resulting in unacceptable electrical performance of the circuitry. A method for purifying the substrate prior to circuitry formation includes forming a sacrificial layer of mercury telluride or mercury cadmium telluride on the substrate, annealing the combination at elevated temperature with an overpressure of mercury and removing the sacrificial layer along with a contiguous portion of the substrate, if desired. The sacrificial layer may be formed by vapor phase type processes or even by liquid phase epitaxy.

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Liverpool, NY, United States of America

Robert W Yanka