Gallium arsenide avalanche photodiode
View Patent ↗An avalanche photodiode can include: an avalanche region having one or more layers prepared from GaAs; an N − absorption layer extending across the avalanche region; an N-type layer above at least a center portion of the N − absorption layer; and optionally a lower conductivity layer laterally from the N-type layer to a surface of the avalanche region and above a perimeter portion of the N − absorption layer, the lower conductivity layer having lower conductivity compared to the N-type layer. The avalanche photodiode can include a window layer above the N-type layer and lower conductivity layer, and an anode contact above the window layer. The avalanche photodiode can include an N + barrier layer below the N − absorption layer, an N + conduction layer below the N + barrier layer, a substrate below the N + conduction layer, and a cathode contact coupled with the N + conduction layer.
1. An avalanche photodiode comprising:
an avalanche region having one or more layers prepared from GaAs
an N − absorption layer extending across the avalanche region;
an N-type layer above at least a center portion of the N − absorption layer; and
a lower conductivity layer laterally from the N-type layer to a surface of the avalanche region and above a perimeter portion of the N − absorption layer, the lower conductivity layer having lower conductivity compared to the N-type layer.
2. The avalanche photodiode of claim 1 , wherein the N-type layer extends across the N − absorption layer.
3. The avalanche photodiode of claim 2 , wherein the N-type layer extends across a mesa having the N-type layer and the N − absorption layer.
4. The avalanche photodiode of claim 1 , wherein the lower conductivity layer having a conductivity reducing implant compared to conductivity of the N-type layer.
5. The avalanche photodiode of claim 4 , wherein the implant is a proton implant or a beryllium implant.
6. The avalanche photodiode of claim 1 , comprising a window layer above the N-type layer, and an anode contact above the window layer.
7. The avalanche photodiode of claim 6 , comprising an N + barrier layer below the N − absorption layer, an N + conduction layer below the N + barrier layer, a substrate below the N + conduction layer, and a cathode contact coupled with the N + conduction layer.
8. The avalanche photodiode of claim 7 , wherein the avalanche region is included in a mesa structure, the mesa extending into the N + conduction layer so that a portion of the N + conduction layer is in the mesa and a portion forms a shoulder from the mesa, with the cathode contact on the shoulder of the N + conduction layer.
9. The avalanche photodiode of claim 8 , comprising:
an oxide layer above the window layer;
a dielectric passivation layer coated onto the window layer and over side surfaces of the mesa;
an anode bond pad coupled with the anode contact;
a cathode bond pad coupled with the cathode contact; and
an environmental-protection passivation layer above the dielectric passivation layer, anode contact, and cathode contact, and the environmental-protection passivation layer having openings that expose the anode bond pad and cathode bond pad.
10. The avalanche photodiode of claim 1 , comprising a window layer above the N-type layer and above the N − absorption layer, the window layer including the lower conductivity layer, and an anode contact above the window layer.
11. The avalanche photodiode of claim 10 , comprising an N + barrier layer below the N − absorption layer, an N + conduction layer below the N + barrier layer, a substrate below the N + conduction layer, and a cathode contact coupled with the N + conduction layer.
12. The avalanche photodiode of claim 11 , wherein the avalanche region is included in a mesa structure, the mesa extending into the N + conduction layer so that a portion of the N + conduction layer is in the mesa and a portion forms a shoulder from the mesa, with the cathode contact on the shoulder of the N + conduction layer.
13. The avalanche photodiode of claim 12 , comprising:
an oxide layer above the window layer;
a dielectric passivation layer coated onto the window layer and over side surfaces of the mesa;
an anode bond pad coupled with the anode contact;
a cathode bond pad coupled with the cathode contact; and
an environmental-protection passivation layer above the dielectric passivation layer, anode contact, and cathode contact, and the environmental-protection passivation layer having openings that expose the anode bond pad and cathode bond pad.
14. An avalanche photodiode comprising:
an avalanche region having one or more layers prepared from GaAs;
a P − absorption layer extending across the avalanche region;
an P-type layer below at least a center portion of the P − absorption layer; and
a lower conductivity region laterally from the P-type layer to a surface of the avalanche region and below a perimeter portion of the P − absorption layer, the lower conductivity region having lower conductivity compared to the P-type layer.
15. The avalanche photodiode of claim 14 , wherein the P − absorption layer extends across the P-type layer.
16. The avalanche photodiode of claim 15 , wherein the P-type layer extends across a mesa having the P-type layer and the P − absorption layer.
17. The avalanche photodiode of claim 14 , comprising a window layer above the P − absorption layer, the P − absorption layer including the lower conductivity region and an anode contact above the window layer.
18. The avalanche photodiode of claim 17 , comprising an N + barrier layer below the P − absorption layer, an N + conduction layer below the N + barrier layer, a substrate below the N + conduction layer, and a cathode contact coupled with the N + conduction layer.
19. The avalanche photodiode of claim 18 , wherein the avalanche region is included in a mesa structure, the mesa extending into the N + conduction layer so that a portion of the N + conduction layer is in the mesa and a portion forms a shoulder from the mesa, with the cathode contact on the shoulder of the N + conduction layer.
20. The avalanche photodiode of claim 19 , comprising:
an oxide layer above the window layer;
a dielectric passivation layer coated onto the window layer and over side surfaces of the mesa;
an anode bond pad coupled with the anode contact;
a cathode bond pad coupled with the cathode contact; and
an environmental-protection passivation layer above the dielectric passivation layer, anode contact, and cathode contact, and the environmental-protection passivation layer having openings that expose the anode bond pad and cathode bond pad.
21. An avalanche photodiode comprising:
an avalanche region having one or more layers prepared from GaAs;
an N − absorption layer extending across the avalanche region;
an N-type layer above at least a center portion of the N − absorption layer; and
an N + barrier layer below the N − absorption layer, an N + conduction layer below the N + barrier layer, a substrate below the N + conduction layer, and a cathode contact coupled with the N + conduction layer.