Etching for GaN laser facets and material characterization

The ability to remove or etch surface materials is a fundamental device processing step and is required to obtain mesa stripes in laser diode fabrication. This is particularly important for GaN-based laser diodes since the substrates, sapphire and SiC, on which the epitaxial materials are grown cannot be easily cleaved. The wide range of dry and wet etching techniques developed for GaN-based materials are described. The dry etching techniques include reactive ion etching (RIE), electron cyclotron RIE, inductively-coupled plasma RIE, chemically-assisted ion beam etching, and low-energy electron enhanced etching. Photoelectrochemical wet etching is used in the etching of n-type GaN.