Non-polar (11-20) GaN grown on sapphire with double overgrowth on micro-rod/stripe templates

Non-polar (11-20) GaN with low defect density can be achieved on sapphire by means of an overgrowth on a micro-rod template recently developed, or on a conventional < 1-100 >-oriented stripe template. The overgrowth on stripes block BSFs in the nonpolar GaN more effectively, but it is difficult to obtain a flat GaN surface due to its anisotropic pattern for overgrowth. The overgrowth on micro-rods can significantly reduce dislocations, simultaneously maintaining a smooth sample surface. Very recently, we develop a double overgrowth approach to grow (11-20) GaN on sapphire, i.e. first overgrowth on stripes and second overgrowth on micro-rods. The double overgrowth technique successfully utilizes the strengths of the two kinds of overgrowths, further improving crystal quality, which will be a very promising approach to achieve high quality (11-20) GaN for large-scale industrial production.