Long wave photo-detection device for used in long wave infrared detection, materials, and method of fabrication
View Patent ↗The disclosure provides a photo-detection device for use in long-wave infrared detection and a method of fabrication. The device comprises a GaSb substrate, a photo absorbing layer comprising InAs/InAsSb superlattice type-II, a barrier layer comprising AlAsSb, and a contact layer comprising InAs/InAsSb superlattice type-II. The barrier layer is configured to allow minority carrier holes current flow while blocking majority carrier electrons current flow between the photo-absorbing and contact layers. The disclosure further provides a method of producing the photo-detector using photolithography which includes selective etching of the contact layer that stops on the top of the barrier so no etching is made to the barrier layer so the barrier may operate as a passivator too. The disclosure presents an x-ray and photoluminescence results for InAs/InAsSb superlattice type-II material. Also present a measurement of a single element, Long-Wave photo-detector, showing very low dark current and very high Quantum efficiency, as predicted.
1. A photo-detector that detects long wave infrared radiation, comprising:
a substrate;
an n-type photo absorbing layer comprising a superlattice type II of periods of InAs(3 nm)/InAs 0.6 Sb 0.4 (2 nm) that exhibits a valence band energy and conducting band energy during operation of the photo-detector deposited on said substrate;
a barrier layer comprising an undoped AlAs 0.13 Sb 0.87 semiconductor having a band energy gap and associated conduction and valence band energies;
a first side of said barrier layer adjacent a first side of said photo absorbing layer;
a contact layer comprising an n-type superlattice type II of periods of InAs(3 nm)/InAs 0.6 Sb 0.4 (2 nm)exhibiting a valence band energy and a conducting band energy during operation of the photo-detector and being adjacent a second side of said barrier layer opposing said first side;
wherein the relationship between the photo absorbing layer and contact layer valence and conduction band energies and the barrier layer conduction and valance band energies facilitates minority carrier holes current flow while inhibiting majority carrier electrons current flow between the contact and photo absorbing layers.
2. A photo-detector according to claim 1 , wherein the photo-detector absorbs infrared radiation greater than or equal to 8 microns.
3. A photo-detector according to claim 1 , wherein said photo absorbing layer, said barrier layer, and said contact layer are created via molecular beam epitaxy.
4. A photo-detector according to claim 1 , wherein the barrier is used for passivation.