ABSTRACT
The use of boron nitride (BN) as a substrate for graphene nanodevices has attracted much interest since the recent report that BN greatly improves the mobility of charge carriers in graphene compared to standard SiO(2) substrates. We have explored the local microscopic properties of graphene on a BN substrate using scanning tunneling microscopy. We find that BN substrates result in extraordinarily flat graphene layers that display microscopic Moiré patterns arising from the relative orientation of the graphene and BN lattices. Gate-dependent dI/dV spectra of graphene on BN exhibit spectroscopic features that are sharper than those obtained for graphene on SiO(2). We observe a significant reduction in local microscopic charge inhomogeneity for graphene on BN compared to graphene on SiO(2).
Subject(s)
Boron Compounds/chemistry , Electrons , Graphite/chemistry , Microscopy, Scanning Tunneling , Particle Size , Silicon Dioxide/chemistry , Surface PropertiesABSTRACT
The potential size and power benefits of resonant NEMS devices are frequently mitigated by the need for relatively large, high-frequency, high-power electronics. Here we demonstrate controllable, sustained self-oscillations in singly clamped carbon nanotubes operating with a single dc voltage supply, and we develop a model that predicts the required voltage on the basis of the material properties and device geometry. Using this model, we demonstrate for the first time top-down, self-oscillating NEMS devices suitable for large-scale integration.
