FIB milling of single-crystal and sputtered ZnO: SEM and AFM characterization

• The morphology of different ZnO substrates after FIB milling has been studied.
• Yield and roughness are evaluated as a function of ion beam dose and milling angle.
• Rough sputter-deposited films can be smoothed at normal ion-beam incidence.
• Off-normal FIB milling on (0 0 0 1) sputtered ZnO produced ordered terracing.
• Single crystal ZnO maintain smooth surfaces regardless of the milling angle.

We report on the morphological study of focused ion beam (FIB) milling of both sputter-deposited and single crystal (0 0 0 1) ZnO substrates. The surface roughness and the FIB induced sputtering yield were measured as a function of the ion dose and angle. Smoothing effect of rough films deposited by sputtering has been found at low ion doses. FIB milling at non-normal incidence produced roughness increase and the formation of ordered terraces on (0 0 0 1)-oriented sputtered ZnO. Conversely, surface roughness and FIB yield on single crystal ZnO substrates is basically unaffected by ion dose and milling angle.

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