W. Kozłowski

Graphene on gold: Electron density of states studies by scanning tunneling spectroscopy

Graphene devices require electric contacts with metals, particularly with gold. Scanning tunneling spectroscopy studies of electron local density of states performed on mono-, bi-, and trigraphene layer deposited on metallic Au/Cr/SiO2/Si substrate shows that gold substrate causes the Fermi level shift downwards which means that holes are donated by metal substrate to graphene which becomes p-type doped. These experimental results are in good accordance with recently published density function theory calculations.

Scanning tunneling microscopy and spectroscopy of Y-junction in carbon nanotubes

Scanning tunneling microscopy and spectroscopy were used to observe the variations of electronic structure on the carbon nanotube Y-junction. The electronic structure derived from tunneling conductance maps showed natural me- tallic-metallic and semiconducting-metallic transitions close to the Y-junction, and the occurrence of metallic character of the whole Y-junction with the presence of additional resonant state at energy of 0.2 eV below the Fermi level. It is suggested that the state originates from heptagons forming the junction. 2002 Elsevier Science B.V. All rights reserved.

The role of water in resistive switching in graphene oxide

The resistive switching processes are investigated at the nano-scale in graphene oxide. The modification of the material resistivity is driven by the electrical stimulation with the tip of atomic force microscope. The presence of water in the atmosphere surrounding graphene oxide is found to be a necessary condition for the occurrence of the switching effect. In consequence, the switching is related to an electrochemical reduction. Presented results suggest that by changing the humidity level the in-plane resolution of data storage process can be controlled. These findings are essential when discussing the concept of graphene based resistive random access memories.

Anisotropic oxidation of bismuth nanostructures: Evidence for a thin film allotrope of bismuth

We present evidence that ultra-thin Bi(110) nanostructures oxidise from the edges, and that their top surfaces remain unoxidised. Even after prolonged oxidation, clean (unoxidised) bismuth is present in nanostructures that are less than 5 monolayers thick. Since the (110) surface of bulk bismuth is known to be readily oxidised, this is strong evidence for a thin film allotrope of bismuth. We present a comparison with calculated structures and the structures of polymeric nitrogen, which suggests that the allotrope is one of several complex or hybrid paired-layer structures.