Development of Ar gas cluster ion beam system for surface preparation in angle-resolved photoemission spectroscopy.

Gas cluster ion beam (GCIB) sputtering has a high potential for obtaining clean and flat surfaces on materials without causing structural or compositional damage. We have developed an Ar cluster GCIB system for surface preparation in angle-resolved photoemission spectroscopy (ARPES). The constructed GCIB system is compatible with ultrahigh vacuum and achieves a beam current of 10 µA. We examined the usefulness of our GCIB system for high surface-sensitive ARPES measurements by applying it to several representative materials, e.g., Sb, GaAs, and Te. The results show that the constructed GCIB system is very useful for preparing a clean flat surface on crystals, widening opportunities for precise ARPES measurements for materials whose crystal surfaces or orientations are hardly obtained by a simple cleaving method.