Study on Surface Modification of GaN by Atmospheric Microplasma

GaN is widely studied and developed as a material for new application in power electronic devices or as an emitter of various colors of light. GaN is usually formed by nitriding GaAs and grown on the sapphire substrate with a high dislocation density. For this dislocation, microchannel epitaxy or regrowth of GaN is required to reduce dislocations. Recently, plasma treatment has been used for interface treatment, regrowing of GaN crystal, and nitridation process of GaAs. GaN surface was treated by atmospheric-pressure microplasma using Ar and N2 as process gases and powered by ac and pulsed-power supplies. Microplasma is atmospheric-pressure nonthermal plasma and a type of dielectric barrier discharge which has a small discharge gap and requires relatively low discharge voltage of only about 1 kV. Modifications of the surface were observed after the treatment, and they depend on the gas process, treatment time, and power supply. The surface was analyzed before and after the treatment using X-ray photoelectron spectroscopy analysis and atomic force microscopy.