Method for epitaxial devices
Epitaxial growth methods and devices are described that include a textured surface on a substrate. Geometry of the textured surface provides a reduced lattice mismatch between an epitaxial material and the substrate. Devices formed by the methods described exhibit better interfacial adhesion and lower defect density than devices formed without texture. Silicon substrates are shown with gallium nitride epitaxial growth and devices such as LEDs are formed within the gallium nitride.
1. A method of forming a light emitting diode device, comprising:
applying a block copolymer to a silicon surface;
organizing the block copolymer into a substantially regular pattern;
selectively etching the silicon surface of using the regular pattern of the organized block copolymer as a mask to form a corresponding textured surface of the substrate;
forming epitaxial gallium nitride on the textured surface, wherein a geometry of the textured surface reduces a lattice mismatch between the epitaxial gallium nitride and the silicon surface; and
forming a P-N junction within the gallium nitride to provide a desired wavelength of light.
2. The method of claim 1 , wherein selectively etching the silicon surface includes forming the textured surface so that a periodicity of the texture corresponds to a value within approximately +/−25% of an integer multiple of the lattice constant of the epitaxial gallium nitride.
3. The method of claim 1 , wherein selectively etching the silicon surface includes forming the textured surface to include a number of regularly spaced pyramidal structures.
4. The method of claim 1 , wherein selectively etching the silicon surface includes forming the textured surface to include a number of regularly spaced conical-shaped structures.
5. The method of claim 1 , wherein selectively etching the silicon surface includes forming the textured surface to include a number of asymmetric angled surfaces.
6. A method of forming a light emitting diode device, comprising:
applying a block copolymer to a semiconductor surface;
organizing the block copolymer into a substantially regular pattern;
selectively etching the semiconductor surface using the regular pattern of the organized block copolymer as a mask to form one or more angled surfaces within the semiconductor surface;
forming an epitaxial material on the one or more angled surfaces; and
forming a P-N junction within the epitaxial material to provide a desired wavelength of light.
7. The method of claim 6 , wherein applying a block copolymer to the semiconductor surface includes applying a di-block copolymer.
8. The method of claim 6 , wherein applying a block copolymer to the semiconductor surface includes applying a tri-block copolymer.
9. The method of claim 6 , wherein applying a block copolymer to the semiconductor surface includes applying a block copolymer to a silicon surface.
10. The method of claim 6 , wherein forming the epitaxial material on the one or more angled surfaces includes forming epitaxial gallium nitride on the one or more angled surfaces.
11. The method of claim 6 , wherein selectively etching the semiconductor surface includes forming the textured surface to include a number of regularly spaced pyramidal structures.
12. The method of claim 6 , wherein selectively etching the semiconductor surface includes forming the textured surface to include a number of regularly spaced conical-shaped structures.
13. The method of claim 6 , wherein selectively etching the semiconductor surface includes forming the textured surface to include a number of asymmetric angled surfaces.