Novel nanostructures formed by semiconductors on metal surfaces

We present novel semiconductor nanostructures that may have an impact in foture nanoelectronics. These quantum structures are obtained upOn condensing in situ, under ultra-high vacuum, silicon or germanium in the submonolayer to monolayer range onto an unreactive noble metal substrate, namely, onto the low-index (100) or (110) suifaces of a silver single crystal. The protocole used is just the reverse of that traditionally employed for the study of the early stages of the formation of Schottky barriers. These nanostructures are observed in scanning tunnelling microscopy either as self-assembled two-dimensional arrays of tetramer nanodots forming ordered superstructures for Ge on Ag(lOO) or Ag(ll0), or as a massively parallel assembly of one-dimensional narrow stripes, reaching eventually hundreds of nanometers in lengthfor Sion Ag(110).