Characterization of reactive ion etched surface of GaN using methane gas with chlorine plasma

Reactive ion etching of GaN has been carried out in two different plasma ch emistries using 10Cl(2)/10Ar and 1CH(4)/9Cl(2)/10Ar at various applied radi o frequency (rf) power. We have addressed the postetch surface characterist ics of GaN, and the effect of CH, addition to chlorine plasma and the varia tion of rf power are discussed. Surface contamination, roughness, and stoic hiometry have been determined from the results of secondary ion mass spectr ometry. It is observed that in the case of plasma with 5% CH4, above 125 W, contamination of carbon is minimal and roughness is similar to that of the as-grown sample. At rf power less than 125 W, the Ga/N ratio of the etched surface is almost unity, whereas at rf power more than 125 W, it is more t han unity. When the GaN surface is etched with only chlorine plasma, the su rface is Ga excess at all rf power applied. The intensity of the main band- to-band photoluminescence peak is found to decrease when 10Cl(2)/10Ar is us ed, and the intensity was a minimum at 200 W. When 5% CH4 is added to the p lasma, the intensity at 200 W became almost the same as that of the as-grow n sample, indicating minimal damage induced in the surface. (C) 2000 Americ an Vacuum Society. [S0734-211X(00)02305-2].