Low light level imager with extended wavelength response employing atomic bonded (fused) semiconductor materials

US5808329A · kind A · utility

Assignee

• Raytheon Company · US

Inventors

• Michael D. Jack · Goleta, US
• Ken Ando · Lompoc, US
• Kenneth Kosai · Goleta, US
• David R. Rhiger · Lompoc, US

Key dates

• Filing date: Jul 15, 1996
• Grant date: Sep 15, 1998
• Expiry date: Jul 15, 2016

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F39/199

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. The layer of narrower bandgap material may be disposed upon a surface of a transparent substrate, and also may be differentiated into a plurality of mesa structures (14a). In further embodiments the absorbing layer may have an equivalent or a wider bandgap than the layer having the readout circuitry.