Tunneling barrier infrared detector devices
View Patent ↗Embodiments of the present disclosure are directed to infrared detector devices incorporating a tunneling structure. In one embodiment, an infrared detector device includes a first contact layer, an absorber layer adjacent to the first contact layer, and a tunneling structure including a barrier layer adjacent to the absorber layer and a second contact layer adjacent to the barrier layer. The barrier layer has a tailored valence band offset such that a valence band offset of the barrier layer at the interface between the absorber layer and the barrier layer is substantially aligned with the valence band offset of the absorber layer, and the valence band offset of the barrier layer at the interface between the barrier layer and the second contact layer is above a conduction band offset of the second contact layer.
1. An infrared detector device comprising:
a first contact layer;
an absorber layer adjacent to the first contact layer; and
a tunneling structure comprising a barrier layer adjacent to the absorber layer and a second contact layer adjacent to the barrier layer, wherein the barrier layer has a tailored valence band offset such that:
a valence band offset of the barrier layer at the interface between the absorber layer and the barrier layer is substantially aligned with the valence band offset of the absorber layer; and
the valence band offset of the barrier layer at the interface between the barrier layer and the second contact layer is above a conduction band offset that is within the second contact layer.
2. The infrared detector device of claim 1 , wherein:
the barrier layer comprises a first barrier layer and a second barrier layer;
the first barrier layer is adjacent to the absorber layer; and
the second barrier layer is adjacent to the second contact layer.
3. The infrared detector device of claim 2 , wherein:
the first barrier layer comprises (GaSb) x (AlAs 0.08 Sb 0.92 ) 1-x lattice matched to GaSb, with x value chosen such that a valence band offset of the first barrier layer is substantially-aligned with a valence band offset of the absorber layer; and
the second barrier layer comprises (GaSb) y (AlAs 0.08 Sb 0.92 ) 1-y , where y>x.
4. The infrared detector device of claim 3 , wherein a base energy level of a quantum well for holes formed by the tunneling structure is greater than the Fermi level.
5. The infrared detector device of claim 3 , wherein a base energy level of a quantum well for holes formed by the tunneling structure is less than the Fermi level.
6. The infrared detector device of claim 1 , wherein the tunneling structure provides a gradual transition from the valence band offset at the interface between the barrier layer and the absorber layer to the valence band offset at the interface between the barrier layer and the second contact layer.
7. The infrared detector device of claim 1 , wherein a transition from the valence band offset at the interface between the barrier layer and the absorber layer to the valence band offset at the interface between the barrier layer and the second contact layer is parabolic.
8. The infrared detector device of claim 1 , wherein a transition from the valence band offset at the interface between the barrier layer and the absorber layer to the valence band offset at the interface between the barrier layer and the second contact layer is rectangular.
9. The infrared detector device of claim 1 , wherein the absorber layer comprises an InAs/InAsSb SLS, InAs/Ga(In)Sb SLS, a digital alloy, or bulk absorber.
10. The infrared detector device of claim 1 , wherein the barrier layer comprises a graded (GaSb) x (AlAsSb) 1-x structure.
11. The infrared detector device of claim 1 , wherein the barrier layer comprises a graded superlattice material.
12. The infrared detector device of claim 11 , wherein the graded superlattice material comprises a AlAsSb/GaSb superlattice structure.