In a two-dimensional IR staring array in which pixel-registered, medium wave and long wave infrared (MWIR, LWIR) images of the same object field are simultaneously readout, a focal plane assembly comprising:
- (A) an LWIR transmissive crystalline first substrate having a first face oriented for front side illumination and a second face oriented for back side illumination,
- (B) an integrated MWIR radiation sensitive metal insulator semiconductor (MIS) charge injection device (CID) detector array formed on said first face for sensing a two-dimensional image comprising:
- (a) a first semiconductor layer of a material suitable for MWIR radiation sensing and absorption epitaxially grown on said first face, and
- (b) an insulated gate structure formed on said first semiconductor layer comprising an IR transparent metallic gate layer patterned to form a two dimensional array of IR transmissive window shaped pixels, and IR opaque metallic conductors for connection to individual pixels lying principally in aisles framing said window shaped pixels, said first semiconductor layer and said gate structure forming an array of MWIR sensing MIS-CID pixels distributed within the boundary of said image, each pixel sensing and absorbing MWIR radiation and constituting an LWIR radiation transmissive window,
- (c) an integrated multiplexer (MUX) for said MWIR detector array comprising switch, preamplifier, multiplexer, and shift register portions, disposed on the back face of a IR transmissive second substrate disposed in front of said first substrate, the IR opaque parts of said switch portion being apertured and laid out in aisles framing said apertures, said aperture and aisles on said second substrate being in registry with said pixels and aisles on said first substrate;
- the preamplifier, multiplexer, and shift register portions of said MWIR MUX being displaced outside said image boundary,
- (C) opaque conductive means aligned with said aisles interconnecting the individual pixels of said MWIR detector array to said MWIR MUX to enable image readout,
- (D) an integrated two-dimensional, LWIR radiation sensitive, photovoltaic (PV) diode array coextensive with said MWIR detector array comprising a second semiconductor layer epitaxially grown on said second face for monolithic integration with said MWIR detector array, said second semiconductor layer being of a material suitable for LWIR radiation sensing;
- and a diffusion on the back face of said second semiconductor layer patterned to provide an array of LWIR radiation sensitive PV diode pixels, the LWIR sensitive regions of said LWIR pixels being aligned with said LWIR radiation transmissive windows of said MWIR detector array to provide image radiation to each pixel of said LWIR detector array in registration with the image provided to each pixel of said MWIR detector array, and
- (E) an integrated LWIR MUX disposed on a third substrate mechanically attached to the back face of said first substrate and electrically connected to individual PV diodes of said LWIR sensitive detector array to enable an LWIR radiation image to be readout simultaneously with and in pixel-registration to the MWIR radiation image.