Infrared detector devices and focal plane arrays having a transparent common ground structure and methods of fabricating the same

A method of fabricating a frontside-illuminated focal plane array, the method comprising:

• providing a wafer comprising a bulk substrate layer, a contact layer disposed on the bulk substrate layer, a detector structure disposed on the contact layer, and a common ground structure disposed on the detector structure, wherein the common ground structure is transmissive to radiation having a desired wavelength, and the common ground structure has a bandgap that is wider than a bandgap of the detector structure;
• bonding an optical layer to the common ground structure;
• thinning the bulk substrate layer of the wafer;
• etching the contact layer and the detector structure to form an array of infrared photodetector devices, each individual infrared photodetector device defining a pixel having a wall, wherein the detector structure is fully reticulated and the common ground structure is partially reticulated;
• and
• forming at least one ground pixel by depositing an electrically conductive layer on a wall of at least one pixel to electrically couple the contact layer of the at least one pixel to the common ground structure.