Schottky diode with buried layer in GaN materials
View Patent ↗A semiconductor structure includes a III-nitride substrate characterized by a first conductivity type and having a first side and a second side opposing the first side, a III-nitride epitaxial layer of the first conductivity type coupled to the first side of the III-nitride substrate, and a plurality of III-nitride epitaxial structures of a second conductivity type coupled to the III-nitride epitaxial layer. The semiconductor structure further includes a III-nitride epitaxial formation of the first conductivity type coupled to the plurality of III-nitride epitaxial structures, and a metallic structure forming a Schottky contact with the III-nitride epitaxial formation and coupled to at least one of the plurality of III-nitride epitaxial structures.
1. A method of fabricating a diode in gallium nitride (GaN) materials, the method comprising:
providing a n-type GaN substrate having a first surface and a second surface;
forming a first n-type GaN epitaxial layer coupled to the first surface of the n-type GaN substrate;
forming a p-type GaN epitaxial layer coupled to the first n-type GaN epitaxial layer;
removing at least a portion of the p-type GaN epitaxial layer to form a plurality of p-type device structures;
forming a second n-type GaN epitaxial layer coupled to the plurality of p-type device structures;
removing at least a portion of the second n-type GaN epitaxial layer to expose a portion of at least one p-type device structure; and
forming a first metallic structure electrically coupled to the exposed portion of the at least one p-type device structure and a remaining portion of the second n-type GaN epitaxial layer, wherein a lateral boundary of the first metallic structure is substantially coincident with a point of contact between the first metallic structure and the exposed portion of the at least one p-type structure.
2. The method of claim 1 wherein the first metallic structure forms a Schottky contact with the remaining portion of the second n-type GaN epitaxial layer.
3. The method of claim 1 wherein the first metallic structure forms an ohmic contact with the exposed portion of the at least one p-type device structure.
4. The method of claim 1 wherein forming the plurality of p-type device structures includes forming one or more edge termination structures.
5. The method of claim 4 wherein the one or more edge termination structures circumscribe the first metallic structure.
6. The method of claim 1 wherein forming the first metallic structure includes forming the first metallic structure such that one or more p-type device structures are disposed between the first n-type GaN epitaxial layer and the first metallic structure.
7. The method of claim 1 further comprising forming a second metallic structure electrically coupled to the second surface of the n-type GaN substrate.
8. The method of claim 1 wherein:
the n-type GaN substrate is characterized by a first n-type dopant concentration; and
the first n-type GaN epitaxial layer is characterized by a second n-type dopant concentration less than the first n-type dopant concentration.
9. A method of fabricating an epitaxial structure, the method comprising:
providing a III-nitride substrate of a first conductivity type;
forming a first III-nitride epitaxial layer of the first conductivity type coupled to a first surface of the III-nitride substrate;
forming a second III-nitride epitaxial layer of a second conductivity type coupled to the first III-nitride epitaxial layer;
removing at least a portion of the second III-nitride epitaxial layer to form a plurality of epitaxial structures of the second conductivity type;
forming a third III-nitride epitaxial layer of the first conductivity type coupled to the plurality of epitaxial structures; and
forming a first metallic structure electrically coupled to at least one of the epitaxial structures and to a portion of the third III-nitride epitaxial layer, wherein a lateral boundary of the first metallic structure is substantially coincident with a point of contact between the first metallic structure and the at least one epitaxial structure.
10. The method of claim 9 wherein forming the third III-nitride epitaxial layer comprises a selective regrowth process.
11. The method of claim 9 further comprising removing at least a portion of the third III-nitride epitaxial layer.
12. The method of claim 9 wherein the first metallic structure is configured to form a Schottky contact with the third III-nitride epitaxial layer.
13. The method of claim 9 wherein the first metallic structure forms an ohmic contact with the at least one of the plurality of epitaxial structures.
14. The method of claim 9 wherein forming the plurality of epitaxial structures includes forming one or more edge termination structures.
15. The method of claim 9 wherein forming the first metallic structure includes forming the first metallic structure such that one or more epitaxial structures are disposed between the first III-nitride epitaxial layer and the first metallic structure.
16. The method of claim 9 further comprising forming a second metallic structure electrically coupled to a second surface of the III-nitride substrate.
17. The method of claim 9 wherein the first conductivity type is n-type and the second conductivity type is p-type.
18. A semiconductor structure comprising:
a III-nitride substrate characterized by a first conductivity type and having a first side and a second side opposing the first side;
a III-nitride epitaxial layer of the first conductivity type coupled to the first side of the III-nitride substrate;
a plurality of III-nitride epitaxial structures of a second conductivity type coupled to the III-nitride epitaxial layer;
a III-nitride epitaxial formation of the first conductivity type coupled to the plurality of III-nitride epitaxial structures; and
a metallic structure forming a Schottky contact with the III-nitride epitaxial formation and coupled to at least one of the plurality of III-nitride epitaxial structures, wherein a lateral boundary of the metallic structure is substantially coincident with a point of contact between the metallic structure and the III-nitride epitaxial formation.
19. The semiconductor structure of claim 18 wherein the first metallic structure forms an ohmic contact with the at least one of the plurality of III-nitride epitaxial structures.
20. The semiconductor structure of claim 18 wherein the plurality of III-nitride epitaxial structures includes one or more edge termination structures.
21. The semiconductor structure of claim 18 wherein one or more of the plurality of III-nitride epitaxial structures is disposed between the III-nitride epitaxial layer and the metallic structure.
22. The semiconductor structure of claim 18 further comprising forming a second metallic structure electrically coupled to the second side of the III-nitride substrate.