High fill-factor ac-coupled x-y addressable Schottky photodiode array
First Claim
1. A Schottky barrier infrared detector array comprising:
- a semiconductor substrate having first and second separate surfaces;
a plurality of unit cells formed on said substrate and arranged in a pattern of rows and columns;
each of said unit cells including;
means disposed in said first surface for receiving incident radiation;
a photosensitive Schottky barrier metal electrode formed on said second surface of said semiconductor substrate and defining a Schottky junction therewith, anda row electrode and a column electrode electrically insulated from said Schottky barrier metal electrode and capacitively coupled to said Sckottky barrier metal electrode, said row and column electrodes overlapping a substantial portion of said Schottky barrier metal electrode so as to achieve a high fill factor;
a set of row address lines each corresponding to a row of said plurality of unit cells and connected to the row electrodes of the unit cells of the corresponding row; and
a set of column address lines each corresponding to a column of said plurality of unit cells and connected to the column electrodes of the unit cells of the corresponding column.
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Accused Products
Abstract
Each unit cell of a Schottky barrier photodiode imaging array comprises a Schottky metal electrode formed on a silicon substrate. The Schottky electrode is reverse biased with a pulse for beginning a sensing interval, following which the change in charge on the electrode is related to the quantity of incident infrared radiation. For X-Y addressable readout, a row electrode and a column electrode are capacitively coupled to each Schottky electrode and connected to row and column address lines. For low overlap capacitance and low stray capacitance, the row and column electrodes are concentric within each cell and coplanar above the Schottky electrode. Over the row and column electrodes is an address line insulating layer, and sets of row and column address lines are coplanar over this layer. Separate segments of each row address line extend between adjacent electrode portions of correspondingly adjacent unit cells, and each column address line extends across a plurality of unit cells between the row address line segments. The address lines are connected to the underlying readout electrodes through contact windows in the address line insulating layer.
26 Citations
20 Claims
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1. A Schottky barrier infrared detector array comprising:
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a semiconductor substrate having first and second separate surfaces; a plurality of unit cells formed on said substrate and arranged in a pattern of rows and columns; each of said unit cells including; means disposed in said first surface for receiving incident radiation; a photosensitive Schottky barrier metal electrode formed on said second surface of said semiconductor substrate and defining a Schottky junction therewith, and a row electrode and a column electrode electrically insulated from said Schottky barrier metal electrode and capacitively coupled to said Sckottky barrier metal electrode, said row and column electrodes overlapping a substantial portion of said Schottky barrier metal electrode so as to achieve a high fill factor; a set of row address lines each corresponding to a row of said plurality of unit cells and connected to the row electrodes of the unit cells of the corresponding row; and a set of column address lines each corresponding to a column of said plurality of unit cells and connected to the column electrodes of the unit cells of the corresponding column. - View Dependent Claims (2, 3, 4, 5, 6, 7, 13, 14, 15, 16, 17, 18, 19)
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8. A Schottky barrier infrared detector element comprising:
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a semiconductor substrate having a first surface and a second surface, said first surface being separate from said second surface; a photosensitive Schottky barrier metal electrode formed on said first surface of said semiconductor substrate and defining a Schottky junction therewith;
said second surface of said semiconductor substrate including means for receiving incident radiation andat least one readout electrode overlying a substantial portion of said Schottky barrier metal electrode and being electrically insulated from and capacitively coupled to said Schottky barrier metal electrode. - View Dependent Claims (9, 11)
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10. A method of operating a Schottky photodiode having a semiconductor substrate including first and second separate surface, a Schottky barrier metal electrode formed on said first surface of semiconductor substrate and defining a Schottky junction therewith and having means for receiving incident radiation disposed in said second surface of said semiconductor substrate, said method comprising:
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capacitively coupling to a substantial portion of the Schottky barrier metal electrode an electrical pulse of voltage magnitude and polarity appropriate to reverse bias the photodiode with a charge quantity therein; and exposing a second surface of said semiconductor substrate to incident radiation, coupling an infrared portion of said incident radiation to said Schottky junction, sensing the infrared portion of the incident radiation, determining the magnitude of charge remaining in the photodiode at the end of a sensing and integration interval by capacitively coupling a signal from the Schottky barrier metal electrode.
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12. An infrared imaging array disposed in a semiconductor substrate and exhibiting a high fill-factor including a plurality of closely spaced Schottky barrier infrared detector elements each comprising:
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a portion of said semiconductor substrate having a first radiation receiving surface and a second detector surface said first radiation receiving surface and second detector surfaces being disposed on nonadjacent surfaces of said semiconductor substrate; a photosensitive Schottky barrier metal electrode disposed in registry with said second detector surface and forming a Schottky barrier junction therewith; and a readout electrode overlapping a substantial portion of said Schottky barrier metal electrode and being electrically insulated from and capacitively coupled to said Schottky barrier metal electrode, and said first radiation receiving surface comprising greater than 30 percent of the corresponding substrate surface. - View Dependent Claims (20)
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Specification