DRY PATTERNING OF INGAN AND INALN

Dry etch rates of InxGa1-xN and InxAl1-xN alloys are found to increase with In mole fraction in CH4/H-2 microwave (2.45 GHz) discharges, and to decrease under the same conditions in Cl2/H-2 mixtures. Both plasma chemistries produce smooth anisotropic etching across the entire composition range from InN to either GaN or AlN. Addition of SF6, rather than H-2, to a Cl2 discharge produces faster etch rates and retains smooth morphologies. This suggests that either atomic hydrogen or fluorine is capable of effective removal of N from the III-V nitride materials. Ar+ ion milling rates for InGaAlN alloys are found to be approximately a factor of 2 lower than for more conventional III-V semiconductors like GaAs.