Patterning of cubic and hexagonal GaN by Cl2/N2-based reactive ion etching

Chlorine-based dry etching of hexagonal and cubic GaN epilayers grown by dc plasma-assisted molecular beam epitaxy is investigated using a conventional parallel electrode reactor. It is found that the addition of nitrogen results in a shallow maximum for etch rates at 37% N2 content in a low-pressure plasma and a monotonically decreasing etch rate in higher-pressure plasmas. Etching with a low-pressure plasma produces smooth surfaces and almost vertical sidewalls at sufficiently high etch rates.