III-N device structures and methods
A III-N device is described with a III-N layer, an electrode thereon, a passivation layer adjacent the III-N layer and electrode, a thick insulating layer adjacent the passivation layer and electrode, a high thermal conductivity carrier capable of transferring substantial heat away from the III-N device, and a bonding layer between the thick insulating layer and the carrier. The bonding layer attaches the thick insulating layer to the carrier. The thick insulating layer can have a precisely controlled thickness and be thermally conductive.
1. A III-N device, comprising:
a substrate having a thickness;
a III-N layer adjacent the substrate;
an electrode adjacent the III-N layer on a side opposite the substrate;
an aperture through the substrate; and
an additional layer in the aperture; wherein
the aperture is through the entire thickness of the substrate but not through an entire thickness of the III-N layer, and the additional layer entirely fills the aperture.
2. The III-N device of claim 1 , wherein the substrate is selected from the group consisting of silicon, silicon carbide, sapphire, and aluminum nitride.
3. The III-N device of claim 1 , wherein the electrode is a gate, a source, or a drain, and the device is a transistor.
4. The III-N device of claim 1 , wherein the aperture is opposite the electrode.
5. The III-N device of claim 1 , wherein the III-N layer comprises a channel layer and a barrier layer.
6. The III-N device of claim 5 , wherein the channel layer is between the barrier layer and the substrate.
7. The III-N device of claim 6 , wherein the channel layer has a thickness, and the aperture is through the entire thickness of the substrate but not through the entire thickness of the channel layer.
8. The III-N device of claim 1 , wherein the electrode is an anode or a cathode and the device is a diode.
9. The III-N device of claim 8 , wherein the diode is a lateral device.
10. The III-N device of claim 1 , wherein the additional layer contacts the III-N layer.
11. The III-N device of claim 10 , wherein the additional layer is about 0.5-20 microns thick.
12. The III-N device of claim 10 , wherein the additional layer extends over a side of the substrate opposite the III-N layer.
13. The III-N device of claim 12 , further comprising a thermally conductive layer contacting the additional layer on a side opposite the III-N layer.
14. The III-N device of claim 13 , wherein the thermally conductive layer is a heat sink.
15. The III-N device of claim 10 , wherein a thermal conductivity of the additional layer is sufficient to dissipate substantial heat from the III-N device.
16. The III-N device of claim 10 , wherein the additional layer passivates the surface of the III-N layer adjacent the aperture.
17. The III-N device of claim 1 , wherein the additional layer is selected from the group consisting of silicon nitride, aluminum nitride, silicon dioxide, alumina, a polymeric dielectric, and an inorganic or an organic dielectric.
18. The III-N device of claim 1 , wherein the additional layer comprises a polymeric or organic dielectric.
19. The III-N device of claim 1 , wherein the aperture is below and around the electrode.
20. A method of making a III-N device comprising:
forming on a substrate, the substrate having a thickness, a structure comprising a III-N layer, the III-N layer being adjacent to the substrate, and the structure having an electrode adjacent the III-N layer on a side of the III-N layer opposite the substrate;
forming an aperture through the substrate; and
depositing an additional layer in the aperture; wherein
the aperture is formed through the entire thickness of the substrate but not through an entire thickness of the III-N material, and the additional layer entirely fills the aperture.
21. The method of claim 20 , wherein the aperture is opposite the electrode.
22. The method of claim 21 , wherein the additional layer contacts the III-N layer.
23. A III-N device, comprising:
a substrate having a thickness;
a III-N material contacting the substrate, wherein a crystalline structure of the III-N material adjacent to the substrate at least partially conforms to or is at least partially determined by a crystalline structure of the substrate;
an electrode adjacent the III-N material on a side opposite the substrate;
an aperture through the entire thickness of the substrate; and
an insulating material in the aperture and contacting the III-N material; wherein
the aperture is opposite the electrode, and the insulating material extends over a side of the substrate opposite the III-N layer.
24. The III-N device of claim 23 , wherein the aperture is through the entire thickness of the substrate but not through an entire thickness of the III-N material.
25. The III-N device of claim 23 , the III-N material comprising a III-N channel layer and a III-N barrier layer, wherein a two-dimensional electron gas is in the III-N channel layer near an interface between the III-N channel layer and the III-N barrier layer.
26. The III-N device of claim 23 , wherein the insulating material comprises silicon nitride, aluminum nitride, silicon dioxide, or alumina.
27. The III-N device of claim 23 , wherein the insulating material comprises a polymeric or organic dielectric.
28. A III-N device, comprising:
a substrate having a thickness;
a III-N material contacting the substrate, the III-N material comprising a III-N channel layer and a III-N barrier layer, wherein a two-dimensional electron gas is in the III-N channel layer near an interface between the III-N channel layer and the III-N barrier layer;
an electrode adjacent the III-N material on a side opposite the substrate;
an aperture through the entire thickness of the substrate; and
an additional layer in the aperture and contacting the III-N material; wherein
the additional layer comprises an element selected from the group consisting of silicon nitride, aluminum nitride, alumina, a polymeric dielectric, and an organic dielectric.
29. The III-N device of claim 28 , wherein the aperture is below and around the electrode.
30. The III-N device of claim 28 , wherein the electrode contacts the two-dimensional electron gas.
31. The III-N device of claim 28 , wherein the electrode is a gate, and the III-N device is a transistor.
32. The III-N device of claim 28 , wherein the channel layer has a thickness, and the aperture is through the entire thickness of the substrate but not through the entire thickness of the channel layer.
33. A III-N device, comprising:
a substrate having a thickness;
a III-N material contacting the substrate, the III-N material comprising a III-N channel layer and a III-N barrier layer, wherein a two-dimensional electron gas is in the III-N channel layer near an interface between the III-N channel layer and the III-N barrier layer;
an electrode adjacent the III-N material on a side opposite the substrate;
an aperture through the entire thickness of the substrate; and
an additional layer in the aperture and contacting the III-N material; wherein
the additional layer comprises an element selected from the group consisting of silicon nitride, aluminum nitride, silicon dioxide, alumina, a polymeric dielectric, and an inorganic or an organic dielectric; and
wherein the additional layer extends over a side of the substrate opposite the III-N layer.