Optimization and shape control of GaN nano pillars fabricated by inductively coupled plasma etching

We report the systematic etching profile of GaN nano pillar structures using inductively coupled plasma (ICP) etching techniques. We were able to control the side wall angle, shape and dimension of such nanoscale structures by carefully selecting the etching parameters. We present the effects of variations of the etch parameters, such as ICP power, RF power, chamber pressure, and substrate temperature on the etch characteristics, such as etch rate, sidewall angle, anisotropy, mask erosion, and surface roughness. Utilizing such methods, we demonstrated the fabrication of nanoscale structures with designed shapes and dimensions over large area. Nanocolumns with diameter of 120 nm and height of 1.6 mu m with sidewall angle of 86 degrees (90 degrees represent a vertical sidewall) were fabricated. Nanocones with tip diameter of 30 nm and height of 1.6 mu m with sidewall angle of 70 degrees were demonstrated. The structures produced by such top-down method could potentially be used in light-emitting diodes, laser diodes, photodetectors, vertical transistors, fielde-mitters, and photovoltaic devices.