Gallium nitride-based schottky barrier diode with aluminum gallium nitride surface layer
View Patent ↗A method of fabricating a Schottky diode using gallium nitride (GaN) materials includes providing an n-type GaN substrate having a first surface and a second surface. The second surface opposes the first surface. The method also includes forming an ohmic metal contact electrically coupled to the first surface of the n-type GaN substrate and forming an n-type GaN epitaxial layer coupled to the second surface of the n-type GaN substrate. The method further includes forming an n-type aluminum gallium nitride (AlGaN) surface layer coupled to the n-type GaN epitaxial layer and forming a Schottky contact electrically coupled to the n-type AlGaN surface layer.
1. A method of fabricating a Schottky diode using gallium nitride (GaN) materials, the method comprising:
providing an n-type GaN substrate having a first surface and a second surface, the second surface opposing the first surface;
forming an ohmic metal contact electrically coupled to the first surface of the n-type GaN substrate;
forming an n-type GaN epitaxial layer coupled to the second surface of the n-type GaN substrate;
forming an n-type aluminum gallium nitride (AlGaN) surface layer coupled to the n-type GaN epitaxial layer; and
forming a Schottky contact electrically coupled to the n-type AlGaN surface layer,
wherein, during operation, an interface between the n-type GaN epitaxial layer and the n-type AlGaN surface layer is substantially free from a two-dimensional electron gas, and
wherein the n-type GaN epitaxial layer comprises a polar GaN material.
2. The method of claim 1 , wherein the n-type AlGaN surface layer is characterized by a thickness between 0.5 nm and 15 nm.
3. The method of claim 2 wherein the thickness is between 1 nm and 3 nm.
4. The method of claim 1 , wherein the n-type AlGaN surface layer is characterized by a graded aluminum mole fraction as a function of thickness.
5. The method of claim 4 wherein the aluminum mole fraction increases as a distance to the Schottky contact structure decreases.
6. A semiconductor device comprising:
a III-nitride substrate having a first surface and a second surface opposing the first surface;
a first metallic structure electrically coupled to the first surface of the III-nitride substrate and forming an ohmic contact with the III-nitride substrate;
a III-nitride epitaxial region characterized by a first bandgap and coupled to the second surface of the III-nitride substrate;
a surface region characterized by a second bandgap and coupled to the III-nitride epitaxial region, wherein the second bandgap is greater than the first bandgap; and
a second metallic structure electrically coupled to the surface region and forming a Schottky contact with the surface region,
wherein, during operation, an interface between the III-nitride epitaxial region and the surface region is substantially free from a two-dimensional electron gas, and
wherein a thickness of the surface region is between 0.5 nm and 15 nm.
7. The semiconductor device of claim 6 , wherein the thickness of the surface region is between 1 nm and 3 nm.
8. The semiconductor device of claim 6 wherein the surface region comprises at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), aluminum indium nitride (AlInN), or aluminum gallium indium nitride (AlGaInN).
9. The semiconductor device of claim 8 wherein a concentration of aluminum of the surface region is graded such that the concentration of aluminum increases as distance to the second metallic structure decreases.
10. A method of fabricating an epitaxial structure, the method comprising:
providing a III-nitride substrate characterized by a certain conductivity type and having a first surface and a second surface, the second surface opposing the first surface;
forming an ohmic contact electrically coupled to the first surface of the III-nitride substrate;
forming a III-nitride epitaxial region of the certain conductivity type coupled to the second surface of the III-nitride substrate, wherein the III-nitride epitaxial region is characterized by a first bandgap;
forming a surface region coupled to the III-nitride epitaxial region, wherein the surface region is characterized by a second bandgap greater than the first bandgap; and
forming a Schottky contact electrically coupled to the surface region,
wherein, during operation, an interface between the III-nitride epitaxial region and the surface region is substantially free from a two-dimensional electron gas, and
wherein the III-nitride epitaxial region comprises a polar material.
11. The method of claim 10 wherein the certain conductivity type is n-type.
12. The method of claim 10 wherein the surface region is characterized by a thickness between 0.5 nm and 15 nm.
13. The method of claim 12 wherein the thickness is between 1 nm and 3 nm.
14. The method of claim 10 wherein the surface region is formed to comprise at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), aluminum indium nitride (AlInN), or aluminum gallium indium nitride (AlGaInN).
15. The method of claim 14 wherein a concentration of aluminum of the surface region is graded such that the concentration of aluminum increases as a distance to the Schottky contact decreases.
16. A method of fabricating a Schottky diode using gallium nitride (GaN) materials, the method comprising:
providing an n-type GaN substrate having a first surface and a second surface, the second surface opposing the first surface;
forming an ohmic metal contact electrically coupled to the first surface of the n-type GaN substrate;
forming an n-type GaN epitaxial layer coupled to the second surface of the n-type GaN substrate;
forming an n-type aluminum gallium nitride (AlGaN) surface layer coupled to the n-type GaN epitaxial layer; and
forming a Schottky contact electrically coupled to the n-type AlGaN surface layer,
wherein, during operation, an interface between the n-type GaN epitaxial layer and the n-type AlGaN surface layer is substantially free from a two-dimensional electron gas, and
wherein the n-type AlGaN surface layer is characterized by a thickness between 0.5 nm and 15 nm.
17. The method of claim 16 wherein the n-type AlGaN surface layer is characterized by a graded aluminum mole fraction as a function of thickness, wherein the aluminum mole fraction increases as a distance to the second metallic structure decreases.
18. The method of claim 17 , wherein the n-type GaN epitaxial layer comprises a polar GaN material.
19. A method of fabricating a Schottky diode using gallium nitride (GaN) materials, the method comprising:
providing an n-type GaN substrate having a first surface and a second surface, the second surface opposing the first surface;
forming an ohmic metal contact electrically coupled to the first surface of the n-type GaN substrate;
forming an n-type GaN epitaxial layer coupled to the second surface of the n-type GaN substrate;
forming an n-type aluminum gallium nitride (AlGaN) surface layer coupled to the n-type GaN epitaxial layer; and
forming a Schottky contact electrically coupled to the n-type AlGaN surface layer,
wherein, during operation, an interface between the n-type GaN epitaxial layer and the n-type AlGaN surface layer is substantially free from a two-dimensional electron gas, and
wherein a concentration of aluminum of the surface layer is graded such that the concentration of aluminum increases as distance to the Schottky contact decreases.
20. A semiconductor device comprising:
a III-nitride substrate having a first surface and a second surface opposing the first surface;
a first metallic structure electrically coupled to the first surface of the III-nitride substrate and forming an ohmic contact with the III-nitride substrate;
a III-nitride epitaxial region characterized by a first bandgap and coupled to the second surface of the III-nitride substrate;
a surface region characterized by a second bandgap and coupled to the III-nitride epitaxial region, wherein the second bandgap is greater than the first bandgap; and
a second metallic structure electrically coupled to the surface region and forming a Schottky contact with the surface region,
wherein, during operation, an interface between the III-nitride epitaxial region and the surface region is substantially free from a two-dimensional electron gas, and
wherein the III-nitride epitaxial region comprises a polar material.
21. The semiconductor device of claim 20 , wherein the surface region comprises at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), aluminum indium nitride (AlInN), or aluminum gallium indium nitride (AlGaInN), and wherein a concentration of aluminum of the surface region is graded such that the concentration of aluminum increases as distance to the second metallic structure decreases.
22. The semiconductor device of claim 20 , wherein a thickness of the surface region is between 0.5 nm and 15 nm.
23. A semiconductor device comprising:
a III-nitride substrate having a first surface and a second surface opposing the first surface;
a first metallic structure electrically coupled to the first surface of the III-nitride substrate and forming an ohmic contact with the III-nitride substrate;
a III-nitride epitaxial region characterized by a first bandgap and coupled to the second surface of the III-nitride substrate;
a surface region characterized by a second bandgap and coupled to the III-nitride epitaxial region, wherein the second bandgap is greater than the first bandgap; and
a second metallic structure electrically coupled to the surface region and forming a Schottky contact with the surface region,
wherein, during operation, an interface between the III-nitride epitaxial region and the surface region is substantially free from a two-dimensional electron gas, and
wherein the surface region comprises at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), aluminum indium nitride (AlInN), or aluminum gallium indium nitride (AlGaInN), and wherein a concentration of aluminum of the surface region is graded such that the concentration of aluminum increases as distance to the second metallic structure decreases.
24. The semiconductor device of claim 23 , wherein the III-nitride epitaxial region comprises a polar material, and wherein a thickness of the surface region is between 0.5 nm and 15 nm.
25. A method of fabricating an epitaxial structure, the method comprising:
providing a III-nitride substrate characterized by a certain conductivity type and having a first surface and a second surface, the second surface opposing the first surface;
forming an ohmic contact electrically coupled to the first surface of the III-nitride substrate;
forming a III-nitride epitaxial region of the certain conductivity type coupled to the second surface of the III-nitride substrate, wherein the III-nitride epitaxial region is characterized by a first bandgap;
forming a surface region coupled to the III-nitride epitaxial region, wherein the surface region is characterized by a second bandgap greater than the first bandgap; and
forming a Schottky contact electrically coupled to the surface region,
wherein, during operation, an interface between the III-nitride epitaxial region and the surface region is substantially free from a two-dimensional electron gas, and
wherein the surface region is characterized by a thickness between 0.5 nm and 15 nm.
26. The method of claim 25 , wherein the surface region is formed to comprise at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), aluminum indium nitride (AlInN), or aluminum gallium indium nitride (AlGaInN), and wherein a concentration of aluminum of the surface region is graded such that the concentration of aluminum increases as a distance to the Schottky contact decreases.
27. The method of claim 26 , wherein the III-nitride epitaxial region comprises a polar material.
28. A method of fabricating an epitaxial structure, the method comprising:
providing a III-nitride substrate characterized by a certain conductivity type and having a first surface and a second surface, the second surface opposing the first surface;
forming an ohmic contact electrically coupled to the first surface of the III-nitride substrate;
forming a III-nitride epitaxial region of the certain conductivity type coupled to the second surface of the III-nitride substrate, wherein the III-nitride epitaxial region is characterized by a first bandgap;
forming a surface region coupled to the III-nitride epitaxial region, wherein the surface region is characterized by a second bandgap greater than the first bandgap; and
forming a Schottky contact electrically coupled to the surface region,
wherein the surface region is formed to comprise at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), aluminum indium nitride (AlInN), or aluminum gallium indium nitride (AlGaInN), and wherein a concentration of aluminum of the surface region is graded such that the concentration of aluminum increases as a distance to the Schottky contact decreases.