InAs/GaSb infrared superlattice photodiodes doped with Beryllium
An improved photodiode and method of producing an improved photodiode comprising doping an InAs layer of an InAs/GaSb region situated on top of an InAs/GaSb:Be superlattice and below an InAs:Si/GaSb regions such that the quantum efficiency of the photodiode increases and dominant dark current mechanisms change from diffusion to band-to-band tunneling as the InAs layer is doped with Beryllium.
1. An InAs/GaSb photodiode comprising:
a GaSb:Be buffer;
an InAs/GaSb:Be superlattice;
an InAs/GaSb active region;
an InAs:Si/GaSb region; and
an InAs:Si contact layer
wherein the InAs/GaSb active region is doped with Beryllium in the InAs layer such that quantum efficiency of the photodiode increases and a dominant dark current mechanism changes from diffusion to band-to-band tunneling as the InAs layer is doped with the Beryllium.
2. The photodiode of claim 1 wherein the GaSb:Be buffer is 250 nm thick, the InAs/GaSb:Be superlattice is 500 nm thick, InAs/GaSb region is 2000 nm thick, the InAs:Si/GaSb region is 500 nm thick, and the InAs:Si contact layer is thin.
3. The photodiode of claim 1 wherein the quantum efficiency increases up to 28%.
4. The photodiode of claim 1 wherein electron mobility is increased at least an order of magnitude greater than hole mobility.
5. The photodiode of claim 1 wherein electron lifetime is increased at least an order of magnitude greater than hole lifetime.
6. The photodiode of claim 1 wherein electron diffusion length is increased at least an order of magnitude greater than hole diffusion length.
7. The photodiode of claim 1 wherein a minority electron concentration dominates.
8. The photodiode of claim 1 wherein diffusion current decreases as the InAs layer is doped with Beryllium.
9. The photodiode of claim 1 wherein a contribution of the diffusion current to an R 0 A product increases proportionally as the InAs layer is doped with Beryllium.