Aluminum gallium nitride etch stop layer for gallium nitride based devices
View Patent ↗A semiconductor structure includes a III-nitride substrate with a first side and a second side opposing the first side. The III-nitride substrate is characterized by a first conductivity type and a first dopant concentration. The semiconductor structure also includes a III-nitride epitaxial layer of the first conductivity type coupled to the first surface of the III-nitride substrate, and a first metallic structure electrically coupled to the second surface of the III-nitride substrate. The semiconductor structure further includes an AlGaN epitaxial layer coupled to the III-nitride epitaxial layer of the first conductivity type, and a III-nitride epitaxial structure of a second conductivity type coupled to the AlGaN epitaxial layer. The III-nitride epitaxial structure comprises at least one edge termination structure.
1. A semiconductor structure comprising:
a III-nitride substrate having a first side and a second side opposing the first side, wherein the III-nitride substrate is characterized by a first conductivity type and a first dopant concentration;
a III-nitride epitaxial layer of the first conductivity type coupled to the first surface of the III-nitride substrate;
a first metallic structure electrically coupled to the second surface of the III-nitride substrate;
an AlGaN epitaxial layer having a first side coupled to the III-nitride epitaxial layer of the first conductivity type; and
a III-nitride epitaxial structure of a second conductivity type coupled to the AlGaN epitaxial layer on a second side of the AlGaN epitaxial layer, the second side being opposite the first side, wherein the III-nitride epitaxial structure comprises at least one edge termination structure.
2. The semiconductor structure of claim 1 further comprising a Schottky contact including a second metallic structure coupled to a portion of the AlGaN epitaxial layer.
3. The semiconductor structure of claim 2 wherein the second metallic structure is further coupled to at least a portion of the at least one edge termination structure.
4. The semiconductor structure of claim 2 wherein the AlGaN epitaxial layer is disposed between the second metallic structure and the III-nitride epitaxial layer of the first conductivity type.
5. The semiconductor structure of claim 1 wherein the AlGaN epitaxial layer is characterized by a thickness less than 30 nm.
6. The semiconductor structure of claim 1 wherein the AlGaN epitaxial layer is characterized by a dopant concentration of greater than 1×10 17 cm −3 .
7. The semiconductor structure of claim 1 wherein the AlGaN epitaxial layer is characterized by an aluminum mole fraction between 0.01 and 0.50.
8. The semiconductor structure of claim 1 further comprising a metallic field plate coupled to the at least one edge termination structure.
9. The semiconductor structure of claim 1 wherein the at least one edge termination structure circumscribes a semiconductor device.
10. The semiconductor structure of claim 9 wherein the semiconductor device comprises a Schottky barrier diode.
11. The semiconductor structure of claim 1 wherein:
the at least one edge termination structure comprises three or more edge termination structures with a plurality of spacings between each of the edge termination structures;
a first spacing is located closer to a semiconductor device than a second spacing; and
a width of the first spacing is smaller than a width of the second spacing.