Method and system for junction termination in GaN materials using conductivity modulation
View Patent ↗A semiconductor structure includes a GaN substrate having a first surface and a second surface opposing the first surface. The GaN substrate is characterized by a first conductivity type and a first dopant concentration. The semiconductor structure also includes a first GaN epitaxial layer of the first conductivity type coupled to the second surface of the GaN substrate and a second GaN epitaxial layer of a second conductivity type coupled to the first GaN epitaxial layer. The second GaN epitaxial layer includes an active device region, a first junction termination region characterized by an implantation region having a first implantation profile, and a second junction termination region characterized by an implantation region having a second implantation profile.
1. A semiconductor structure comprising:
a GaN substrate having a first surface and a second surface opposing the first surface, wherein the GaN substrate is characterized by a first conductivity type and a first dopant concentration;
a first GaN epitaxial layer of the first conductivity type coupled to the second surface of the GaN substrate; and
a second GaN epitaxial layer of a second conductivity type coupled to the first GaN epitaxial layer, wherein the second GaN epitaxial layer comprises:
an active device region;
a first junction termination region in contact with the active device region of the second GaN epitaxial layer, characterized by an implantation region having a first implantation profile; and
a second junction termination region in contact with the first junction termination region of the second GaN epitaxial layer, characterized by an implantation region having a second implantation profile.
2. The semiconductor structure of claim 1 further comprising a metallic structure electrically coupled to the first surface of the GaN substrate.
3. The semiconductor structure of claim 1 further comprising a Schottky contact electrically coupled to the active device region.
4. The semiconductor structure of claim 3 wherein the active device region further comprises:
an exposed portion of the first GaN epitaxial layer; and
a Schottky contact electrically coupled to the exposed portion of the first GaN epitaxial layer.
5. The semiconductor structure of claim 3 further comprising:
a metallic field plate coupled to the Schottky contact and extending laterally over at least a portion of the first junction termination region; and
a dielectric layer electrically isolating the first junction termination region from the metallic field plate.
6. The semiconductor structure of claim 1 wherein the active device region includes at least a portion of a PN diode, the PN diode comprising at least a portion of the first GaN epitaxial layer and at least a portion of the second GaN epitaxial layer.
7. The semiconductor structure of claim 1 wherein the active device region includes one or more elements of a JFET.
8. The semiconductor structure of claim 1 wherein the active device region includes at least a portion of a vertical Schottky diode.
9. The semiconductor structure of claim 1 wherein the first junction termination region circumscribes the active device region.
10. The semiconductor structure of claim 9 wherein the second junction termination region circumscribes the first junction termination region.