US 12,408,364 B2
Hole draining structure for suppression of hole accumulation
Hyeongnam Kim, Chandler, AZ (US); and Mohamed Imam, Chandler, AZ (US)
Assigned to INFINEON TECHNOLOGIES AUSTRIA AG, Villach (AT)
Filed by Infineon Technologies Austria AG, Villach (AT)
Filed on May 5, 2021, as Appl. No. 17/308,854.
Prior Publication US 2022/0359739 A1, Nov. 10, 2022
Int. Cl. H10D 30/47 (2025.01); H10D 62/815 (2025.01); H10D 62/824 (2025.01); H10D 62/85 (2025.01)
CPC H10D 30/4738 (2025.01) [H10D 62/8164 (2025.01); H10D 62/824 (2025.01); H10D 62/8503 (2025.01)] 5 Claims
OG exemplary drawing
 
1. A semiconductor structure, comprising:
a substrate;
a first layer formed over the substrate;
a superlattice formed on the first layer;
a hole draining structure that is either formed in an upper part of the superlattice or forms a separate layer above the superlattice;
a p-type aluminum gallium nitride layer formed on the hole draining structure;
a channel layer over the p-type aluminum gallium nitride layer,
wherein the superlattice comprises a first set of layers having a first material type and a second set of layers having a second material type, wherein the first set of layers is interleaved with the second set of layers,
wherein the superlattice below the hole draining structure has an effective first concentration of metal material throughout a thickness of the superlattice below the hole draining structure, the effective first concentration being less than a concentration of metal material in the first layer,
wherein the p-type aluminum gallium nitride layer comprises a second concentration of the metal material that is less than the effective first concentration,
wherein the hole draining structure has an effective graded concentration of the metal material that decreases moving from a first interface between the hole draining structure and the superlattice below the hole draining structure to a second interface between the hole draining structure and the p-type aluminum gallium nitride layer,
wherein the hole draining structure has a third concentration of the metal material at the first interface and a fourth concentration of the metal material at the second interface,
wherein the third concentration is greater than the second concentration of the metal material and less than the effective first concentration of the metal material, and
wherein the fourth concentration of the metal material is greater than the second concentration of the metal material, less than the effective first concentration of the metal material, and less than the third concentration of the metal material.