Zero-bias anomaly in one-dimensional ultrathin metallic nanowires AIP Advances 2, 032143 (2012) Influence of electron scatterings on thermoelectric effect ZnO nanowires were grown between two Au electrodes on an Al 2 O 3 -deposited Si wafer. Photoresponse, photoresponse spectrum, and current-voltage (I -V) studies were performed for the investigation into photoconduction mechanism in these nanowires. The photoresponse of the nanowires under the continuous illumination of light with above-or below-gap energies was slow, which indicates that photocurrent in the nanowires is surface-related rather than bulk-related. The photoresponse spectrum represents the above-and below-gap absorption bands for the photocurrents. The I -V characteristics under the illumination of the above-gap light are ohmic, but the characteristics under the illumination of the below-gap light are Schottky. This observation indicates that the above-gap light lowers the potential barrier built in the contact between the ZnO nanowires and electrodes, but that the below-gap light does not lower the potential barrier.

, has been utilized as capacitor dielectrics and gate oxides in memory devices owing to its high dielectric constant, very low permeability, and high thermal conductivity.[1±3] In nanotube-based electronics, the importance of Al 2 O 3 nanotubes will increase, for these tubes will be useful in the fabrication of nanocables, nanojacks, [4] and nanocapacitors.[5] Al 2 O 3 nanotubes have recently been prepared by etching a porous alumina membrane template, [6] by using a carbon nanotube template, [7] or via an electrochemical anodization of Al/Si in dilute sulfuric acid using porous alumina films. [4,5] Nevertheless, these preparation methods have some difficulties in controlling and achieving uniformity of the thickness of the Al 2 O 3 nanotubes. In the study reported here, an easy and convenient route to fabricate Al 2 O 3 nanotubes with conformally uniform thickness using ZnO nanowires as templates was developed. First, ZnO/Al 2 O 3 core/shell nanofibers were prepared by depositing Al 2 O 3 on ZnO nanowires by atomiclayer deposition (ALD), then amorphous Al 2 O 3 nanotubes were fabricated by wet-etching the ZnO core nanowires in the ZnO/Al 2 O 3 core/shell nanofibers. The thickness of the Al 2 O 3 nanotubes was precisely controlled by the number of ALD reaction cycles. A scanning electron microscopy (SEM) image of bare ZnO nanowires, and transmission electron microscopy (TEM) images of a ZnO/Al 2 O 3 core/shell nanofiber and an Al 2 O 3 nanotube are presented in Figure 1. The SEM image of Figure 1a shows a side view of the ZnO nanowires synthesized on a Si substrate by a thermal evaporation procedure; the diameter of the nanowires is in the range of 20±200 nm, and the length is 20±30 lm. In this procedure, a thick polycrystalline ZnO layer was first formed on the Si substrate by thermal evaporation of ZnO powder, and the ZnO nanowires were then COMMUNICATIONS 422

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Photoluminescence, absorption, and photocurrent measurements were made for a hybrid system of 1-thioglycerol-capped HgTe nanoparticles synthesized by colloidal method to investigate the photocurrent mechanism in this hybrid system. Absorption and photoluminescence spectra taken for the capped HgTe nanoparticles reveal strong exciton peaks in the near-infrared wavelength range. The wavelength dependence of the photocurrent for these capped nanoparticles is very close to that of the absorption spectrum. For the photocurrent mechanism of the hybrid system, on the basis of our experimental results and energy diagram for the 1-thioglycerol-capped HgTe nanoparticles, it is suggested in this letter that holes among electron-hole pairs created by incident photons in the HgTe nanoparticles are transferred to capping 1-thioglycerol while electrons are strongly confined in these nanoparticles and that the holes contribute to the photocurrent flowing in the medium of 1-thioglycerol.