UW MRSEC IRG 1 Nuggets

Phonon Scattering in Intrinsic Graphene using Tight-binding Bloch Waves (2011)

Thu, 17 Mar 2011 11:16:30 -0500

Fig. 1 Probability density for a Bloch wave with wave vector k=(14.5, 7.9) nm-1, calculated using the nearest-neighbor tight-binding technique.

[Image458]The overall interest in graphene as a material for devices has led to tremendous advances in the knowledge of transport in graphene. However, there are still questions about the intrinsic limit to electron mobility. Recent experiments have demonstrated mobility greater than 107 cm2/Vs at 50 K temperature, exceeding previous theoretical predictions of the intrinsic mobility limit. Here, we present a simple model of phonon scattering rates in intrinsic graphene using electronic....

Transport in Ultra-Thin Silicon Membranes (2011)

Thu, 17 Mar 2011 11:13:52 -0500

Fig. A Top: Square symbols are the conductance of a 120 nm thick silicon membrane as a function of a back-gate voltage. The blue line is the simulated conductance without a direct contribution from mobile electrons in the surface pi* band. The blue curve includes such a contribution, and it is a much better fit to the experimental data. The lower panel shows the calculated Fermi level at both the surface and the back interface.

[Image457]Nanostructures are extremely sensitive to their surface properties. In the past year we have made extensive measurements of thin silicon films in ultra-high vacuum. We now have strong evidence that ultra-thin silicon with a 2x1 surface reconstruction is heavily influenced by the surface pi* band. Fig. A shows experimental measurements (black squares) of the conductance as a function of a back gate voltage for a membrane of thickness 120nm. There is a clear minimum in conductance....

Semiconductor Nanomembrane Tubes: Three-Dimensional Confinement for Controlled Neurite Outgrowth (2011)

Thu, 17 Mar 2011 11:09:16 -0500

In many neural culture studies, neurite migration on a flat, open surface does not reflect the three-dimensional (3D) microenvironment in vivo. With that in mind, we fabricated arrays of semiconductor tubes using strained silicon (Si) and germanium (Ge) nanomembranes and employed them as a cell culture substrate for primary cortical neurons. Our experiments show that the SiGe substrate and the tube fabrication process are biologically viable for neuron cells. We also observe that neurons are....