Abstract: An imaging device (10, 10') has a plurality of unit cells (11) that contribute to forming an image of a scene. The imaging device includes a layer of wide bandgap semiconductor (18) material (e.g., silicon) having photogate charge-mode readout circuitry (20, 22, 24), such as CCD or CMOS circuitry, disposed upon a first surface of the layer. In one embodiment a second, opposing surface of the layer is bonded at a heterojunction interface or atomic bonding layer (16) to a surface of a layer of narrower bandgap semiconductor material (e.g., InGaAs or HgCdTe), that is selected for absorbing electromagnetic radiation having wavelengths longer than about one micrometer (i.e., the NIR or longer) and for generating charge carriers. The generated charge carriers are transported across the heterojunction interface for collection by the photogate charge-mode readout circuitry.