Conventional reactive ion etching of epitaxially grown GaN on (0001) sapphi
re substrate has been investigated using a basic chemistry of SiCl4, Ar and
SF6. Photoresist oy:plasma-deposited SiNx were used for masking. The influ
ence of gas flow pressure and rf-power on the etch rate and morphology,were
studied. A maximum etch rate of 430 nn/min was obtained at an rf power of
300 W. Very smooth surfaces and reasonable etch rates (+/-100 nm/min): were
obtained using the same chemistry:at a lower rf-power of 105 W (de bias of
+/-290 V). The chemical and complementary roles of chlorine and fluorine w
ill be demonstrated.