Formation of substantially pit free indium gallium nitride
View Patent ↗A method of fabricating a device layer structure includes providing a III-nitride semiconductor layer which is bonded to a bonding substrate. A device layer structure is formed on a nitrogen polar surface of the III-nitride semiconductor layer. The device layer structure includes an indium gallium nitride layer with a metal polar surface adjacent to the nitrogen polar surface of the III-nitride semiconductor layer.
1. A method of fabricating a device layer structure, comprising:
providing a gallium nitride semiconductor layer carried by a growth substrate, wherein the gallium nitride semiconductor layer has a gallium polar surface and a nitrogen polar surface closer to the growth substrate than the gallium polar surface;
bonding the gallium nitride semiconductor layer to a first bonding substrate, wherein the gallium nitride semiconductor layer has the gallium polar surface closer to the first bonding substrate than the nitrogen polar surface;
removing the growth substrate such that the gallium nitride semiconductor layer is carried by the first bonding substrate; and
growing at least a portion of a device layer structure comprising an indium gallium nitride material on the nitrogen polar surface of the gallium nitride semiconductor layer after removing the growth substrate such that the indium gallium nitride material is a nitrogen polar grown InGaN material, the indium gallium nitride material including a nitrogen polar exposed surface on a side thereof opposite the gallium nitride semiconductor layer;
wherein the nitrogen polar grown InGaN material includes a light-emitting region, the device layer structure comprising a single layer of the indium gallium nitride material grown pseudomorphically below a critical thickness of the single layer of the indium gallium nitride material on the gallium nitride semiconductor layer.
2. The method of claim 1 , wherein the indium gallium nitride material includes a metal polar surface adjacent to the nitrogen polar surface of the gallium nitride semiconductor layer.
3. The method of claim 1 , wherein the gallium nitride semiconductor layer is a seed layer.
4. The method of claim 1 , wherein a solubility of indium in the indium gallium nitride material is increased in response to growing the indium gallium nitride material on the nitrogen polar surface of the gallium nitride semiconductor layer relative to a solubility of indium in the indium gallium nitride material when grown on a metal polar surface of a gallium nitride semiconductor layer.
5. The method of claim 1 , wherein sizes of pits in the exposed surface of the indium gallium nitride material are reduced in response to growing the indium gallium nitride material on the nitrogen polar surface of the gallium nitride semiconductor layer relative to sizes of pits in an exposed surface of the indium gallium nitride material when grown on a metal polar surface of a gallium nitride semiconductor layer.
6. The method of claim 1 , wherein removing the growth substrate includes removing a portion of the gallium nitride semiconductor layer.
7. The method of claim 1 , further including bonding the indium gallium nitride material to a second bonding substrate and removing the first bonding substrate from the gallium nitride semiconductor layer.
8. The method of claim 1 , further including reducing the defect density of the gallium nitride semiconductor layer proximate to the nitrogen polar surface.
9. The method of claim 8 , further including using at least one of wet and mechanical etching to reduce the defect density.
10. The method of claim 1 , further comprising forming the indium gallium nitride material defining the light-emitting region of the device layer structure to comprise about 20% or more indium.