Bulletin of the American Physical Society
2007 APS Four Corners Section/SPS Zone 16 Joint Fall Meeting
Volume 52, Number 14
Friday–Saturday, October 19–20, 2007; Flagstaff, Arizona
Session C1: Nanodevices |
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Chair: Richard Vanfleet, Brigham Young University Room: Chemistry (Bldg. 20) Room 224 |
Friday, October 19, 2007 3:25PM - 3:37PM |
C1.00001: Schottky Diodes using SWNT networks Bryan Hicks, Stephanie Getty, David Allred Schottky diode-like behavior was observed across a network of single-walled carbon nanotubes (SWCNTs) with asymmetric metal electrodes. The network of SWCNTs was grown on a SiO2/Si substrate using catalyst-assisted chemical vapor deposition (CVD). Using shadow masks, two sets of metal electrodes were deposited onto the SWCNT network. Each device was contacted using one gold electrode and one aluminum electrode. This technique, recently reported in the literature, has formerly only been implemented across well aligned, non-networked SWCNTs. Although no effort was made to align the SWCNTs in our devices or to eliminate metallic nanotubes, current rectification was observed in the source-drain bias range of -3V to +3V. The leakage current ranges between 5 and 22 percent of the current carrying capacities. Maximum forward-biased current capacities between 8 microamps and 22 microamps have been observed with 136,000 ohms to 375,000 ohms series resistances, respectively. Efforts to further characterize the electronic nature and optimize the diode response of the network devices will be discussed. [Preview Abstract] |
Friday, October 19, 2007 3:37PM - 3:49PM |
C1.00002: Schottky Barrier of CoSi2 Nanowires on Si Lifeng Hao, Peter Bennett We report in situ measurements of the Schottky barrier for epitaxial CoSi2 nanowires on Si(100) using a UHV-STM. Defect-free nanowires of CoSi2 with atomically prefect facets and interface (see Fig.1)are grown by depositing Co onto a heated substrate in UHV. Nanowires length and width can be controlled by varying the deposition temperature. Electrical contact is made by disabling the feedback loop then lowering the tip until the current saturates. With such a controlled approach, repeated contacts can be made without significantly damaging the STM tip. An example of I-V curve is shown in Fig. 2, for the nanowire shown in the inset at room temperature. For the various nanowires, we find that the ideality factor decreases with nanowire width but is insensitive to nanowire length in the range -80$^{\circ}$C to +100$^{\circ}$C. It varies strongly with nanowire shape and interface. The departure from ideal values (n $\sim $ 1, phi $\sim $ 0.6eV) is believed to result from enhanced tunneling due to the small nanowire width and shape, which creates a strong electric field at the interface. The tunneling contribution may be decoupled from thermionic current via its temperature dependence. [Preview Abstract] |
Friday, October 19, 2007 3:49PM - 4:01PM |
C1.00003: Fabrication of silicon nanowires on suspended carbon nanotubes Jun Song, Robert Davis, Richard Vanfleet Thin silicon films (15nm) were deposited on single walled and multiwalled carbon nanotubes by low pressure chemical vapor deposition. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to study coated nanotubes both after deposition and following a 600 C annealing step. On the multiwalled tubes the silicon deposition resulted in conformal films, however on the single walled nanotubes, isolated the silicon particles were formed. There was no evidence of silicon carbide formation at the interface of silicon and the carbon. [Preview Abstract] |
Friday, October 19, 2007 4:01PM - 4:13PM |
C1.00004: A Single-walled Carbon Nanotube-based Nanocompass for High Spatial Resolution Magnetometry. Johnathan Goodsell, Jon Brame, Stephanie Getty A design for single walled carbon nanotube (SWCNT) nanocompass will be presented.~ The operating principle exploits the sensitivity of SWCNT electrical properties to strain. The sensor design resembles a classical compass that features an electronic readout.~ It consists of a suspended network of electrically contacted SWCNTs supporting a magnetically responsive, high aspect-ratio Fe component.~ During operation, torque on the Fe needle in a magnetic field will induce a strain on the suspended SWCNTs, which is measurable as a change in electronic properties of the device.~ We will discuss fabrication of the magnetometer, preliminary data, including magnetic field and temperature dependence of the SWCNT network material, and calculations to estimate the nanocompass sensitity to magnetic field.~ We will also outline future work planned at BYU in collaboration with NASA's Goddard Space Flight Center. [Preview Abstract] |
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