Nanohole Pattern Formation on Germanium Induced by Focused Ion Beam and Broad Beam Ga+ Irradiation

Hexagonally ordered nanohole patterns were produced on Ge(100) surfaces by focused Ga+ ion beam and by broad Ga+ ion beam irradiations with 5 keV energy under normal incidence. Identical patterns were obtained by irradiations with a scanning focussed ion beam under dierent irradiation conditions and with a broad Ga+ beam without scanning and ve orders of magnitude smaller ion flux. Thus we could demonstrate that nanohole pattern formation is independent of ion flux over several orders of magnitude and scanning of a FIB under appropriate conditions is identical to broad ion beam irradiation.