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ABSTRACT: Four-level nonvolatile small-molecule 4F(2) memory cells were developed with a sandwiched device structure consisting of an upper Al electrode, upper small-molecule layer (Alq(3), aluminum tris(8-hydroxyquinoline)), Ni nanocrystals surrounded by NiO tunneling barrier, lower small-molecule layer, and bottom Al electrode. In particular, an in situ O(2)-plasma oxidation process following Ni evaporation was developed to produce uniformly stable 10 nm Ni nanocrystals surrounded by a NiO tunneling barrier embedded in the small-molecule layer. They presented a memory margin (I(on)/I(off) ratio) of approximately 1 x 10(3), a retention time of more than 10(5) s, an endurance of more than 5 x 10(2) erase-and-program cycles, and multilevel cell (MLC) operation, being a terabit nonvolatile memory-cell. A vertically double-stacked 4F(2) multilevel nonvolatile memory cell was also developed, showing a memory margin of approximately 1 x 10(3) in both the top and bottom memory cells and eight-level cell operation.
Nano Letters 05/2009; 9(4):1713-9. · 13.20 Impact Factor
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ABSTRACT: Thin high-quality gallium nitride (GaN) nanowires were synthesized by a catalytic chemical vapor deposition method. The synthesized GaN nanowires with hexagonal single-crystalline structure had thin diameters of 10-50 nm and lengths of tens of micrometers. The thin GaN nanowires revealed UV bands at 3.481 and 3.285 eV in low-temperature PL measurements due to the recombination of donor-bound excitons and donor-acceptor pairs, respectively. The blue shifts of UV bands in the low-temperature PL measurement were observed, indicating quantum confinement effects in the thin GaN nanowires which have smaller diameters than the exciton Bohr radius, 11 nm. For field emission properties of GaN nanowires, the turn-on field of GaN nanowires was 8.5 V/microm and the current density was about 0.2 mA/cm(2) at 17.5 V/microm, which is sufficient for the applications of field emission displays and vacuum microelectronic devices. Moreover, the GaN nanowires indicated stronger emission stability compared with carbon nanotubes.
The Journal of Physical Chemistry B 07/2005; 109(22):11095-9. · 3.70 Impact Factor
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ABSTRACT: Vertically aligned ZnO nanowires have been synthesized on Si substrate by catalyst-free thermal evaporating metallic zinc powder at a low temperature of 600 °C. Studies found that the ZnO nanowires are single-crystalline wurtzite structures with 70 nm in diameter and 10 μm in length. The turn on field of the ZnO nanowires was about 6.2 V/μm at a current density of 0.1 μA/cm2, and the emission current density reached 1 mA/cm2 at an applied field of about 15.0 V/μm. Field emission property from the ZnO nanowires was enough high level to be applicable to field emission displays and vacuum microelectronic devices.
Chemical Physics Letters.
