Ordering of Ge nanocrystals using FIB nanolithography

Formation and ordering of Ge nanocrystals (NC) are studied on Si(0 0 1) and SiO2/Si(0 0 1) substrates patterned by focused ion beam (FIB). In both cases we use a three step process consisting of FIB milling of hole patterns with various periodicities, ex-situ substrate cleaning to remove Ga contamination and Ge NC growth by molecular beam epitaxy (MBE). We show that Ge NC can be ordered between or inside the holes on patterned Si(0 0 1) substrates and inside the holes on patterned SiO2/Si(0 0 1) substrates.