Plural-wavelength infrared detector devices
First Claim
1. A plural wavelength infrared detector device including first and second detector elements comprising respective first and second infrared sensitive semiconductor materials, and a substrate carrying the detector elements, the first semiconductor material having a smaller bandgap than the second semiconductor material so as to provide each first detector element with a response to a longer infrared wavelength, each detector element comprising a pn junction between opposite conductivity-type regions of the respective semiconductor materials, and electrical connections from the detector-element regions to the substrate, wherein the improvement comprises that the electrical connection between the substrate and one region of the longer wavelength response detector element extends on a side wall of both the first and second semiconductor materials, and in that the larger bandgap second material comprises a further region which adjoins the side wall and which forms a further pn junction electrically in parallel with the pn junction of the first detector element, the further pn junction having a higher impedance than the pn junction of the first detector element in the smaller bandgap first material.
2 Assignments
0 Petitions
Accused Products
Abstract
An infrared detector device for at least two wavelengths, i.e. 3 to 5 microns and 8 to 14 microns, comprises detector elements (10 and 20) formed in two or more infrared-sensitive materials with different badgaps, e.g. in cadmium mercury telluride. These materials may be provided side-by-side in a single level on a substrate (3) or preferably as different levels (1 and 2) on the substrate (3). Each detector element (10 and 20) comprises a p-n junction (11 and 21) between opposite conductivity type regions (12,13 and 22,23). Electrical connections (15,25,24) extend from these regions to the substrate (3). Freedom in design and fabrication is obtained by a connection structure in which one connection (25) of the longer-wavelength response element (20) contacts both the semiconductor material (2) of that element (20) and the larger-bandgap material (1) of the shorter-wavelength response element (10), at a side-wall (42) of both materials. The larger-bandgap material (1) comprises a further region (18) which adjoins the side-wall (42) and which forms a further p-n junction (19) electrically in parallel with the p-n junction (21) of the longer-wavelength detector element (20).
40 Citations
7 Claims
- 1. A plural wavelength infrared detector device including first and second detector elements comprising respective first and second infrared sensitive semiconductor materials, and a substrate carrying the detector elements, the first semiconductor material having a smaller bandgap than the second semiconductor material so as to provide each first detector element with a response to a longer infrared wavelength, each detector element comprising a pn junction between opposite conductivity-type regions of the respective semiconductor materials, and electrical connections from the detector-element regions to the substrate, wherein the improvement comprises that the electrical connection between the substrate and one region of the longer wavelength response detector element extends on a side wall of both the first and second semiconductor materials, and in that the larger bandgap second material comprises a further region which adjoins the side wall and which forms a further pn junction electrically in parallel with the pn junction of the first detector element, the further pn junction having a higher impedance than the pn junction of the first detector element in the smaller bandgap first material.
Specification