Synergy Effect of Particle Radiation and Ultraviolet Radiation from Capacitively Coupled Radio Frequency Argon Plasmas on n-GaN Etching Damage

摘要

The change in the morphology of n-GaN surfaces etched by capacitively coupled RF Ar plasmas has been studied from the viewpoint of a synergy effect of particle radiation and UV radiation from the RF plasmas. The particle radiation (in particular, the energy of Ar~+ impinging on n-GaN) is intensified with decreasing gas pressure from 200 to 10mTorr, whereas the intensity of the UV radiation (whose peak wavelength corresponds to the GaN band-gap energy) is significantly weakened. The reverse result occurs when the gas pressure increases. Each type of radiation brings about a smooth surface morphology similar to that of the as-grown surface. However, at 50 or 100 mTorr, at which both types of radiation are expected to coexist, the surface morphology shows various types of pits (defects or dislocations), which seem to be induced by the synergy effect.