Morphology controlled growth of GaN microstructures on graphene for flexible light emitting diodes

Abstract

Recently semiconductor materials have great attention for the achievement of technologies such as graphene and GaN. The graphene got a Nobel Prize at 2010. The graphene is suitable for optoelectronic devices such as optically transparency, flexibility, and mechanically strong. Above all things, the graphene can be easily lift off from substrate because bonding between layers is very week. The GaN materials also got a Nobel Prize at 2014. The GaN materials improve the efficiency of light emitting diodes (LEDs). The GaN has many properties such as high carrier mobility, high recombination rate, and long term stability. Therefore, the growth of GaN LEDs on graphene layers have both advantages of graphene and GaN materials. The combination of GaN materials and graphene will lead to wearable display. The goal of this research is mainly morphology control of GaN microstructures such as pyramid shape, disk shape, and rod shape on graphene layers. However, it is hard to grow GaN microstructures on graphene layers directly. The buffer layer should grow between the graphene and GaN microstructures. Conventionally the GaN LEDs coated on ZnO nanotube or nanowires, but in this research the GaN micro-rods minimize dependency of the buffer layer. Finally, the high aspect ratio GaN micro-rods are grown on thin ZnO nanowall. To fabricate high quality of LEDs, it is important to control quantum wells. The GaN/InxGa1-xN is coated on GaN micro-rods, which has a large area of p-n junctions. Optical characteristics show the spectrum of blue light.