Multi-quantum-well infrared sensor array in spatially-separated multi-band configuration

A device, comprising:

• a substrate formed of a semiconductor;
• a common contact layer formed on said substrate;
• a focal plane imaging array having a first sensing region formed over said common contact layer and having a plurality of adjacent first sensing pixels responsive to radiation at a first spectral band, and a second sensing region formed over said common contact layer and spatially separated from said first sensing region, said second sensing region having a plurality of adjacent second sensing pixels responsive to radiation at a second spectral band,
• wherein each of said first and said second sensing pixels has a plurality of multiple-quantum-well (MQW) structures respectively responsive to different spectral bands formed over said common contact layer in a stack, and a plurality of contact layers to sandwich each MQW structure in combination with said common contact layer;
• a plurality of optical gratings of an electrically conductive material formed on top of said first and said second sensing pixels and having grating teeth extending to at least one layer in each sensing pixel,
• wherein, in said first sensing region, a corresponding grating formed on top of a corresponding contact layer over a top MQW structure has grating teeth extended only in said corresponding contact layer, and in said second sensing region, a corresponding grating formed on top of a corresponding contact layer over a top MQW structure has grating teeth to penetrate through said top MQW structure to form an electrical short;
• at least one first electrically conductive vias formed in said first sensing region with one end in contact with said common detector layer to electrically short each MQW structure underneath said top MQW structure in all first sensing pixels;
• and
• at least one second electrically conductive vias formed in said first sensing region with one end in contact with said common detector layer to electrically short each MQW structure underneath a second MQW structure immediately below said top MQW structure in all second sensing pixels.

A method, comprising:

• providing a substrate formed of a semiconductor;
• forming a common contact layer on said substrate;
• forming a plurality of multiple-quantum-well (MQW) structures respectively responsive to different spectral bands formed over said common contact layer in a stack;
• forming a plurality of contact layers to sandwich each MQW structure in combination with said common contact layer;
• patterning said MQW structures and contact layers to form an array of sensing pixels;
• electrically shorting MQW structures in a first region of said array to leave one MQW structure responsive to a first spectral band;
• and
• electrically shorting MQW structures in a second region of said array to leave one MQW structure responsive to a second spectral band different from said first spectral band.