Etching processes for fabrication of GaN/InGaN/AlN microdisk laser structures

Abstract

Several new wet and dry etch processes required for fabrication of microdisk lasers in the III nitrides have been developed. ICl/Ar electron cyclotron resonance plasmas produce etch rates of 1.3 μm/min for GaN and 1.15 μm/min for InN at 1000 W microwave power and 250 W of rf power. These rates are substantially faster than previously investigated Cl2/Ar or CH4/H2 plasma chemistries. Selectivities of 5–6 over AlN are obtained for these materials. Wet chemical etching of AlN and InXAl1−XN in KOH-based solutions was found to be a strong function of etch temperature and material quality. The activation energy for these materials was in the range 2–6 kcal/mol, typical of diffusion-controlled processes. The KOH solutions did not etch GaN or InN at temperature as high as 80 °C.