Inductively coupled plasma etching of GaN using SiCl_4/Cl_2/Ar for submicron-sized features fabrication

摘要

In this paper we report the optimization of the fabrication process of a grating coupler, which is fully integrated with a GaN planar waveguide. To our knowledge, this is the first report of a grating-assisted optical coupler in gallium nitride. ICP dry etching of n-doped GaN layers was investigated, where SiCl_4/Cl_2/Ar gas mixture was used under different etching conditions. We report n-GaN ICP etching ratio of 520-2680 A min~(-1) as well as etching selectivity of GaN over SiO_2 from 3 to 8, in the most cases. Grating ridge and grating groove width as well as the sidewalls slope were evaluated by SEM microscope.