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US 4,231,053 AGranted
High electrical frequency infrared detector
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorRichard B. Schoolar
Life of this patent
Estimating the term…
Abstract
A thin-film single-crystal infrared detector exhibiting an increased freqcy of response. A closed transverse junction, formed by diffusing a central electrode of an impurity rich metal into a lead-salt film epitaxially grown on an insulating substrate, provides an effective optical area in excess of the junction surface. An ohmic contact is spaced apart from the central electrode. Junction capacitance, a limitation upon the electrical response, is diminished by the detector geometry while detectivity is enhanced. In an alternative embodiment the detector may be segmented to provide directional detection.
Claims60
A photovoltaic detector, comprising:
- an electrically insulating substrate of an alkali-halide;
- an epitaxial layer twelve hundred or less Angstrom units thick of semiconductor material having a first type conductivity, deposited on said substrate;
- the material selected from the group consisting of:
- lead chalcogenides,
- cadmium chalcogenides,
- or mixtures thereof:
- two major surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- a rectifying contact disposed on an area coplanar with one of said major surfaces when said layer is at about room temperature;
- a region formed in situ by the induced field of the rectifying contact;
- the region having a second and opposite type conductivity;
- and
- a P-N junction formed by the contiguous surfaces of said region and said layer.
9 more elements
A semiconductor device comprising:
- an electrically insulating crystalline substrate of an alkali-halide;
- an epitaxial layer not thicker than twelve hundred Angstrom units of semiconductor material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length, disposed on said substrate;
- the material selected from the group consisting of:
- lead chalcogenides,
- cadmium chalcogenides,
- or mixtures thereof;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- a non-ohmic contract affixed to an area coplanar with said top surface when said layer is at about room temperature;
- a region of second and opposite type conductivity formed in situ in said layer by the induced field of the non-ohmic contact;
- said region extending between and terminating in, the two opposed major surfaces, and having two opposed end surfaces, each end surface being coplanar with a different one of the major surfaces, one of the end surfaces including the area;
- the region having a minority charge carrier concentration, and a minority charge carrier diffusion length;
- a P-N junction formed by the contiguous surfaces of said region and said layer.
9 more elements
A photovoltaic detector, comprising:
- an electrically insulating crystalline substrate of an alkali-halide;
- an epitaxial layer having a thickness not greater than twelve hundred Angstrom units of semiconductor material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length L.sub.e, deposited on said substrate;
- the material selected from the group consisting of:
- lead chalcogenides,
- cadmium chalcogenides,
- or mixtures thereof;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- an ohmic contact affixed to said layer at a zone of the first type conductivity;
- a plurality of spaced apart rectifying contacts deposed upon a plurality of areas of said top surface when said layer is at about room temperature;
- the areas being spaced apart from the ohmic contact;
- a plurality of non-contiguous regions of second and opposite type conductivity disposed into said layer;
- the regions formed in situ by the induced fields of the rectifying contacts;
- the regions having a minority charge carrier diffusion length L.sub.r ;
- and
- a plurality of P-N junctions formed by the contiguous surfaces of said regions and said layer.
12 more elements
A photodetector, comprised of:
- an electrically insulating substrate of an alkali-halide;
- an epitaxial layer of material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length, deposited on the substrate;
- the material selected from the group consisting of:
- lead chalcogenide alloys,
- cadmium chalcogenide alloys,
- or mixtures thereof;
- the epitaxial layer having a thickness not greater than nine hundred Angstrom units;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- a first electrical contact affixed to and in an electrically conducting relationship with, said layer at a zone of the first type conductivity;
- a rectifying contact disposed upon an area of said top surface when said layer is at room temperature;
- and
- the area being apart from the first electrical contact and in an electrically conducting relationship with the second electrical contact.
9 more elements
A photodetector, comprised of:
- an electrically insulating substrate of an alkali-halide;
- an epitaxial layer of material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length, deposited upon the substrate;
- the material selected from the group consisting of:
- lead chalcogenide alloys,
- cadmium chalcogenide alloys,
- or mixtures thereof:
- the layer having a thickness not in excess of twelve hundred Angstrom units, and having a top surface opposite a substrate-mating surface;
- an ohmic contact disposed upon a zone of one of the surfaces;
- a rectifying contact disposed upon an area of one of the surfaces when the layer is at room temperature;
- and
- the area being apart from the zone.
8 more elements
A photodetector, comprising:
- an electrically insulating crystalline substrate;
- an epitaxial layer of semiconductor material having a predetermined first type conductivity, deposited on said substrate;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- a region of second and opposite type conductivity disposed into said layer;
- said region extending between and terminating in, the two opposed major surfaces, and having two opposed end surfaces, each end surface being coplanar with a respective one of the major surfaces;
- the material of said region formed in situ by the diffusion of impurities of said second and opposite type conductivity;
- the P-N junction formed by the contiguous surfaces of the material of said region and said layer;
- a first electrical contact affixed to, and in an electrically conducting relationship with, said layer at an area of first type conductivity;
- a second electrical contact affixed to, and in an electrically conducting relationship with, said region of second type conductivity;
- and
- a plurality of detached electrical insulators radiating from said region, each extending between said major opposed surfaces, across the material of said layer having a first type conductivity and through said first electrical contact.
8 more elements
A photodetector, comprising:
- an electrically insulating crystalline substrate;
- an epitaxial layer of semiconductor material having a predetermined first type conductivity, deposited on said substrate;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- a region of second and opposite type conductivity disposed into said layer;
- said region extending between and terminating in, the two major opposed surfaces, and having two opposed end surfaces, each end surface being coplanar with a respective one of the major surfaces;
- the material of said region formed in situ by the diffusion of impurities of said second and opposite type conductivity;
- a P-N junction formed by the contiguous surfaces of the material of said region and said layer;
- a first electrical contact affixed to, and in an electrically conducting relationship with, said layer at a point of first type conductivity;
- a second electrical contact affixed to, and in an electrically conducting relationship with, said region of second type conductivity;
- said second electrical contact being affixed to that opposed end surface coplanar with said top surface;
- and
- a plurality of detached electrical insulators radiating from said region, each extending between said major opposed surfaces, across the material of said layer having a first type conductivity, and through said first electrical contact, adjacent pairs of insulators defining equal arcs.
9 more elements
A photodetector, comprising:
- an electrically insulating crystalline substrate;
- an epitaxial layer of semiconductor material having a predetermined first type conductivity, a predetermined minority charge carrier concentration, and a predetermined minority charge carrier diffusion length, deposited on said substrate;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- a region of second and opposite type conductivity disposed into said layer;
- said region extending between and terminating in, the two opposed major surfaces, and having two opposed end surfaces, each end surface being coplanar with a respective one of the major surfaces;
- each said end surface having a width not less than twice the minority charge carrier diffusion length of said region;
- the material of said region formed in situ by the diffusion of impurities of said second and opposite type conductivity, and having a predetermined minority charge carrier concentration and a predetermined minority charge carrier diffusion length;
- a P-N junction formed by the contiguous surfaces of the material of said region and said layer;
- a first electrical contact affixed to, and in electrically conducting relationship with, said layer at a zone of first type conductivity;
- a second electrical contact affixed, to and in an electrically conducting relationship with, said region of second type conductivity;
- said second electrical contact overlying the area of that opposed end surface coplanar with said top;
- said first electrical contact surrounding, but separated by a distance on the order of the minority charge carrier diffusion length of said epitaxial layer from, said second electrical contact;
- a plurality of detached electrical insulators radiating from said region, each extending between said major opposed surfaces, across the material of said epitaxial layer having a first type conductivity, and through said first electrical contact;
- whereby absent said first conductor, the material of said epitaxial layer having a first type conductivity adjoining opposite sides of any of said electrical insulators is electrically coupled only through said region.
11 more elements
A photodetector, comprising:
- an electrically insulating, crystalline substrate;
- an epitaxial layer of semiconductor material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length L.sub.e, deposited on said substrate;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- at least one region of a second and opposite type conductivity disposed into said layer;
- each said region extending between and terminating in, the two opposed major surfaces, each end surface being coplanar with a respective one of the major surfaces;
- said end surfaces on both major surfaces arrayed concentrically and centered upon a central region having a width on the order of twice the diffusion length L.sub.r, with adjacent end surfaces separated by a distance on the order of the diffusion length L.sub.e ;
- the material of each said region formed in situ by the diffusion of impurities of said second and opposite type conductivity, and having a predetermined minority charge carrier diffusion length L.sub.r ;
- every boundary between material of said layer having the first type conductivity and a region being a P-N junction;
- a first electrical contact disposed on one of said major surfaces and surrounding the outermost of the coplanar of said end surfaces at a distance on the order of the minority charge carrier diffusion length L.sub.e ;
- and
- said first electrical contact and said epitaxial layer except for said central region being radially divided into segments by a plurality of electric insulators.
8 more elements
A photodetector, comprising:
- an electrically insulating, cyrstalline substrate of an alkali-halide;
- an epitaxial layer of semiconductor material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length L.sub.e, deposited on said substrate;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- at least one region of a second and opposite type conductivity disposed into said layer;
- each said region extending between and terminating in two opposed end surfaces, each end surface being coplanar with a respective one of the major surfaces;
- said end surfaces on both major surfaces arrayed concentrically and centered upon a central region having a width on the order of twice the diffusion length L.sub.r, with adjacent end surfaces separated by a distance on the order of the diffusion length L.sub.e ;
- the material of each said region formed in situ by the diffusion of impurities of said second and opposite type conductivity, and having a minority charge carrier diffusion length L.sub.r ;
- every boundary between material of said layer having the first type conductivity and a region being a P-N junction;
- a first electrical contact disposed on one of said major surfaces and surrounding the outermost of the coplanar of said end surfaces at a distance on the order of the minority charge carrier diffusion length L.sub.e ;
- and said first electrical contact being radially divided into a plurality of segments overlying equal areas of said top surface.
7 more elements
A photodetector, comprising:
- an electrically insulating, crystalline substrate;
- an epitaxial layer of semiconductor material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length L.sub.e, deposited on said substrate;
- two major opposed surfaces being, respectively, the top and the substrate-mating surfaces of said layer;
- at least one region of a second and opposite type conductivity disposed into said layer;
- each said region extending between and terminating in, the two opposed major surfaces, each end surface being coplanar with a respective one of the major surfaces;
- said end surfaces on both major surfaces arrayed concentrically and centered upon a central region having a width on the order of twice the diffusion length, L.sub.r, with adjacent end surfaces separated by a distance on the order of the diffusion length L.sub.e ;
- the material of each said region formed in situ by the diffusion of impurities of said second and opposite type conductivity and having a predetermined minority charge carrier diffusion length L.sub.r ;
- every boundary between material of said layer having the first type conductivity and a region being a P-N junction;
- a first electrical contact disposed on one of the said major surfaces and surrounding the outermost of the coplanar of said end surfaces at a distance on the order of the minority charge carrier diffusion length L.sub.e ;
- and
- a plurality of detached electrical insulators radiating from said central region, each insulator extending between said major opposed surfaces through the material of said layer, and through said first electrical contact.
8 more elements
A photodetector, comprised of:
- an epitaxial layer of material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length;
- the material selected from the group consisting of:
- lead chalcogenide alloys,
- cadmium chalcogenide alloys,
- or mixture thereof;
- two major opposed surfaces being, respectively, the top and the bottom surfaces of said layer;
- a first electrical contact affixed to and in an electrically conducting relationship with, said layer at a zone of the first type conductivity;
- a rectifying contact disposed upon an area of said top surface when said layer is at room temperature;
- and
- the area being spaced apart from the first electrical contact and in an electrical conducting relationship with the second electrical contact.
7 more elements
A photodetector, comprised of:
- an epitaxial layer of material having a first type conductivity, a minority charge carrier concentration, and a minority charge carrier diffusion length;
- the material selected from the group consisting of:
- lead chalcogenide alloys,
- cadmium chalcogenide alloys,
- or mixtures thereof:
- the layer having a thickness not in excess of twelve hundred Angstrom units, and having a top surface opposite a bottom surface;
- an ohmic contact disposed upon a zone of one of the surfaces;
- a rectifying contact disposed upon an area of one of the surfaces when the layer is at room temperature;
- and
- the area being apart from the zone.
7 more elements
A photodetector, comprised of:
- an epitaxial layer of material selected from the group consisting of:
- lead chalcogenide alloys,
- cadmium chalcogenide alloys,
- or mixtures thereof;
- an ohmic contact disposed upon a zone on a surface of the layer;
- a rectifying contact disposed upon an area on a surface of the layer when the layer is at room temperature;
- and
- the area being apart from the zone.
5 more elements
Dependencies are inferred from the claim text.