Local oxidation of InN and GaN using an atomic force microscope

Local oxidations of InN and GaN were realized using an atomic force microscope (AFM). InN was oxidized easily by traditional AFM oxidation to similar to 40 nm oxide height. The same AFM methodology was applied to GaN, which exhibited only minimum oxidation even at 10 V and high humidity. However, further experimentation led to successful nano-oxidation of GaN by two different techniques. In the first technique, a similar to 10 nm gold film was deposited by sputtering onto the clean GaN Substrate. The gold film reduced the AFM oxidation circuit resistance and increased the oxyanion driving current (oxidation current), thereby allowing AFM oxidation with heights reaching similar to 25 nm at a humidity of 70%, but with a danger of gold contamination of the oxide. To eliminate this danger, additional experiments were performed in which the gold film on the GaN was removed in a small area, after which AFM oxidation was successfully performed in the area with gold removed with oxidation heights comparable to those of the gold-covered GaN. The techniques in this Study make possible fast, chemical-free and contamination-free AFM nano-oxidation for metal-oxide-semiconductor field effect transistors based on two important nitrides.