Systems, methods, and devices for reducing optical and electrical crosstalk in photodiodes
Devices, systems, and methods are provided for reducing electrical and optical crosstalk in photodiodes. A photodiode may include a first layer with passive material, the passive material having no electric field. The photodiode may include a second layer with an absorbing material, the second layer above the first layer. The photodiode may include a diffused region with a buried p-n junction. The photodiode may include an active region with the buried p-n junction and having an electric field greater than zero. The photodiode may include a plateau structure based on etching through the second layer to the first layer, the etching performed at a distance of fifteen microns or less from the buried p-n junction.
1. An avalanche photodiode, comprising:
a first layer comprising passive material;
a second layer comprising an absorbing material, the second layer on the first layer;
an active region comprising a buried p-n junction and at least a first portion of the second layer, and the active region having an electric field greater than zero; and
a plateau structure based on an absence of a second portion of the second layer, the plateau formed by a trench in the second layer extending downward to the first layer.
2. The avalanche photodiode of claim 1 , further comprising a third layer on the second layer, wherein the buried p-n junction is disposed in the third layer.
3. The avalanche photodiode of claim 2 , wherein the absence of the second portion of the second layer is based on a removal of the second portion of the second layer at a distance greater than zero from the buried p-n junction, and
wherein the removal is based on etching from the third layer to the first layer.
4. The avalanche photodiode of claim 3 , wherein at the distance, the electric field in the second layer is either zero or not zero.
5. The avalanche photodiode of claim 3 , wherein an amount of crosstalk between at least two pixels of the avalanche photodiode is based on a selection of the distance.
6. The avalanche photodiode of claim 3 , wherein the distance is based on an amount of passivation associated with the avalanche photodiode.
7. The avalanche photodiode of claim 3 , wherein the distance is based on a strength of the electric field of the active region.
8. The avalanche photodiode of claim 1 , wherein the absence of the second portion of the second layer is based on a removal of the second portion of the second layer at a distance of fifteen microns or less from the buried p-n junction.
9. The avalanche photodiode of claim 1 , wherein the absence of the second portion of the second layer is based on a removal of the second portion of the second layer, and
wherein the removal is based on etching from a third layer to the first layer.
10. The avalanche photodiode of claim 1 , wherein the passive material comprises an electric field equal to zero.
11. An avalanche photodiode, comprising:
a first layer comprising passive material;
a second layer comprising an absorbing material, the second layer on the first layer;
a third layer on the second layer;
an active region comprising a buried p-n junction and having an electric field greater than zero, the active region comprising at least a first portion of the second layer and at least a first portion of the third layer; and
a plateau structure based on a first absence of a second portion of the second layer and a second absence of a second portion of the third layer.
12. The avalanche photodiode of claim 11 , wherein the first absence and the second absence are at a distance greater than zero from the buried p-n junction.
13. The avalanche photodiode of claim 12 , wherein the first absence and the second absence are based on a removal of the second portion of the second layer and the second portion of the third layer at the distance, the distance being fifteen microns or less from the buried p-n junction.
14. The avalanche photodiode of claim 12 , wherein at the distance, the electric field in the second layer is either zero or not zero.
15. The avalanche photodiode of claim 12 , wherein an amount of crosstalk between at least two pixels of the avalanche photodiode is based on a selection of the distance.
16. The avalanche photodiode of claim 12 , wherein the distance is based on at least one of an amount of passivation associated with the avalanche photodiode, or a strength of the electric field of the active region.
17. The avalanche photodiode of claim 11 , wherein the passive material comprises an electric field equal to zero.
18. A method for forming a photodiode, comprising:
forming a first layer comprising passive material;
forming a second layer comprising an absorbing material, the second layer on the first layer;
forming a diffused region comprising a buried p-n junction;
forming an active region comprising the buried p-n junction and having an electric field greater than zero; and
forming a plateau structure based on removal of a portion of the second layer to the first layer to form a trench in the second layer extending downward to the first layer.
19. The method of claim 18 , wherein the removal is performed at a distance from the buried p-n junction, and at the distance the electric field in the second layer is either zero or not zero.
20. The method of claim 19 , wherein an amount of crosstalk between at least two photodiode pixels is based on a selection of the distance.