Progress in reactive ion etching of epitaxial GaN

Reactive Ion Etching (RIE) of GaN epitaxially grown on (0001) sapphire substrate has been investigated using various chemistries based on SiCl/sub 4/, Ar and SF/sub 6/. Plasma deposited SiN/sub x/ is used for masking. We studied the influence of gas flow, pressure and RF-power on etch rate and morphology. High etch rates up to 150 nm/min can be obtained when using SIC/sub 4/:Ar:SF/sub 6/ (10:10:2 sccm) at an acceleration voltage of 370 Volts. Very smooth surfaces and good etch rates (/spl plusmn/100 nm/min) were obtained using the same chemistry at a lower RF-power of 105 Watts (DC-bias of /spl plusmn/290 V).