Highly anisotropic, ultra-smooth patterning of GaN/SiC by low energy electron enhanced etching in DC plasma

Hetero-epitaxial films of GaN(0001), deposited on SiC(0001) by organometallic vapor phase epitaxy and masked by 200 nm of SiO2 have been patterned by low energy electron enhanced etching (LE4) in hydrogen and chlorine de plasmas at room temperature. Lines 2.0 mu m wide showed highly anisotropic etching: straight side walls, no overcut, no trenching, and no ''pedestal'' at the base of the line. Root mean square (RMS) surface roughness of the films as grown was 8.5-10 Angstrom; after LE4, RMS surface roughness of the etched surfaces was 2.5 Angstrom.