Strained-layer superlattice focal plane array having a planar structure
| DWPI Title: Infrared focal plane array photodetector has passivation layer etched to form two-dimensional array of openings defining space for photodetector elements, and doped region extending down through superlattice to isolate elements |
| Abstract: An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and InxGa1−xSb with 0≰x≰0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 μm. |
| Use: Infrared focal plane array photodetector. |
| Advantage: Surface recombination can be reduced or eliminated, while avoiding the use of mesa structure for electrical isolation between photodetector elements. |
| Novelty: The photodetector (10) has a strained-layer superlattice (SLS) (30) above III-V compound substrate (14). The SLS is comprised of alternating layers of indium arsenide and indium gallium antimonide with specific amount of indium content. A passivation layer (18) is formed above III-V compound layers (16) and etched to provide two-dimensional array of spaced apart openings (20) defining location for formation of photodetector element (12). An impurity-doped region (22) is formed extending down through SLS, to isolate the photodetector elements from adjacent elements. |
| Filed: 8/17/2007 |
| Application Number: US2007840263A |
| Tech ID: SD 10366.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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