Lianzhen Cao

Effects of film thickness and preferred orientation on the dielectric properties of (Bi1.5Zn0.5) (Zn0.5Nb1.5) O7 films

(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 (BZN) films with different thicknesses and preferred orientations have been fabricated on Nb doped SrTiO3 substrates by pulsed laser deposition. As the thickness increases, the permittivity increases, and the dielectric loss decreases, while the tunability only has a little variation. The asymmetric behaviour of the electric field dependent permittivity reduces gradually with the increasing thickness, which should be attributed to the decrease in the effect of the interfacial layer between the dielectric film and substrate (electrode). Furthermore, compared with the (1 0 0) oriented BZN film, BZN film with (1 1 1) preferred orientation exhibits high dielectric loss. (Some figures in this article are in colour only in the electronic version)

Effect of interface barrier between carbon nanotube film and substrate on field emission

The influence of interface barrier on field emission of carbon nanotubes (CNTs) was investigated theoretically and experimentally. A double-potential barrier model was proposed to calculate the electron tunneling probability through the interface and surface barriers. The calculation result reveals that the difference of the electron tunneling probability through the two barriers is responsible for the nonlinearity of the Fowler–Nordheim (FN) plots for the field emission of the CNTs. To verify this model, a series of the CNTs were synthesized on the Si substrates covered with different thicknesses of SiO2 layers as the interface barrier. Based on their field emission properties, it was found that the FN plots of the field emission of these CNTs deviated from the FN law when the applied electric fields were over a critical value, which was strongly dependent on the thicknesses of the SiO2 layer. Therefore, the interface barrier has an important role in determining the field emission property of the CNTs. T...

C-axial oriented (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 thin film grown on Nb doped SrTiO3 substrate by pulsed laser deposition

A c-axial oriented (Bi1.5Zn0.5)(Zn0.5Nb1.5)O-7 thin film has been grown on a (001) Nb doped SrTiO3 substrate by pulsed laser deposition. The permittivity, dielectric loss and tunability of the c-axial oriented film are 187, 0.002 and 6% ( at 750 kV cm(-1) biasing), respectively, indicating a figure of merit of 30. Moreover, an asymmetry behaviour is observed in the dc electric field dependence of permittivity, which could be attributed to the asymmetry of top and bottom electrodes.

Visualization and investigation of Si-C covalent bonding of single carbon nanotube grown on silicon substrate

It has been predicted that the electronic properties of carbon nanotubes (CNTs) can be dramatically tuned by forming Si–C bonds with a silicon surface. Thus, the realization of Si–C bonds will broaden future applications of CNTs on nanodevices. In this paper, we use micro-Raman imaging and spectroscopy to investigate the interaction between individual CNTs and silicon substrate. We show that covalent bonds were formed between certain CNTs and the substrate, and visualized such Si-CNT bonds using micro-Raman imaging. Polarized Raman results further reveal that the Si–C bonds are arranged orderly along the long axis of the Si-CNT. We thus show that Raman imaging is a very useful technique to study properties of such Si-CNTs.

Photoluminescence Studies of SiC/SiO2 Aloetic-Shaped Nanowires

Room- and variable-temperature photoluminescence from 3C-SiC aloetic-shaped nanowires was presented. The SiC nanowires were prepared on Si(100) substrates by the reaction of methane with silicon dioxide. Scanning electron microscope (SEM) and X-ray diffraction (XRD) are used to characterization the nanowires. A green photoluminescence (PL) band centered at 2.34 eV is observed in the nanowires at room temperature. The results from variable-temperature photoluminescence show anomalous temperature dependencies of the spectral characteristics. The emission intensity increases with decreasing temperature until reaching an intensity maximum at about 155 K, then it decreases at lower temperatures. The emission energy has little shift following temperature variations. The anomalous temperature dependencies of PL results may be explained by quantum confinement effect and phonon participation in the emission process.

Y-junction silicon carbide nanowires

Summary form only given. Silicon carbide nanowires with junctions are considered to be of potential value in nanoelectronics. A simple method by catalyst-assisted vapor-liquid-solid reaction for producting Y-junction silicon carbide nanowires is described. The Y-junction silicon carbide nanowires are investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that all the Y-junctions have a predominant branching angle around 90°C, roughly twice the reported bending angle of single bend junctions. The reasons of formation Y-junction may be caused by gas flow fluctuate as reported in reference. This finding provides a possibility for SiC nanowires application in nanoelectronics.

Synthesis and characterization of SiC/SiO 2 nanowires grown on Si (100) substrate

Summary form only given. Large scale SiC/SiO2 nanowires have been synthesized on Si (100) by the reaction of methane with silica using iron as catalyst. The growth time was 10 mins and the growth temperature was around 1,250°C in a normal atmospheric pressure. Detailed investigation with scanning electron microscopy (SEM), energy-dispersed X-ray (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirm that the SiC/SiO2 nanowires consist of a uniform cubic β-SiC core and an amorphous silica shell. The SiC/SiO2 nanowires have a diameter about 30~50 nm and length about 10 μm. Analysis of SEM and TEM results indicated that the nanowires have a large growth rate than that reported. The large growth rate may owe to two reasons: One may be attributed to plentiful carbon atoms (Methane as the carbon resource can be completely decomposed at a temperature 1250°C) and the other may be the hydrogen gas supplied at the growth process.