Wei-Jen Hsieh

The effect of argon on the electron field emission properties of α-C:N thin films

Abstract Amorphous carbon nitride (α-C:N) thin films were synthesized on silicon as electron emitters by the electron cyclotron resonance chemical vapor deposition (ECR-CVD) system in which a negative dc bias was applied to the graphite substrate holder and a mixture of C2H2 and N2 was used as precursors. The addition of Ar combined with the application of a negative dc bias can increase nitrogen content (N/C) measured by X-ray photoelectron spectroscopy (XPS), eliminate the dangling bonds in the film determined by Fourier transform infrared (FTIR) spectroscopy, decrease the film thickness measured by field emission scanning electron microscope (FE-SEM), increase the film roughness measured by atomic force microscope (AFM) and raise the graphitic content examined by Raman spectroscopy. The result shows that the onset emission field of α-C:N with Ar addition to the precursors can be as low as 4.5 V μm−1 compared with 9.5 V μm−1 of the film without the addition of Ar.

Morphology and characterization of highly nitrogenated, aligned, amorphous carbon nano-rods formed on an alumina template by ECR-CVD

Abstract Highly nitrogenated amorphous carbon (a-C:N) nano-rods on a porous alumina template were synthesized using an electron cyclotron resonance chemical vapor deposition (ECR-CVD) system, in which a negative DC bias was applied to the graphite substrate holder to promote the flow of ionic fluxes through the nano-channels of the alumina template in a microwave-excited plasma of C 2 H 2 and N 2 as precursors. The aligned structure of a-C:N nano-rods was verified by field-emission scanning electron microscopy (FE-SEM). Transmission electron microscopy (TEM) micrographs of a-C:N nano-rods showed that the nano-rods are well aligned with a diameter of approximately 100–250 nm and a length of approximately 50–80 μm. The amorphous nature of the nano-rods was confirmed by the absence of crystalline phases arising from selected-area diffraction (SAD) patterns. X-Ray photoelectron spectroscopy (XPS) spectra indicated that these nano-rods were composed of nitrogen and carbon, and the N/C ratios could reach as high as 56%. The absorption bands between 1250 and 1750 cm −1 in Fourier-transform infrared (FTIR) spectra provided direct evidence for the effective incorporation of nitrogen atoms into the amorphous carbon network. Raman spectra showed the same feature, with a G-band at ∼1580 and a D-band at ∼1370 cm −1 in the amorphous carbon film. The well-aligned a-C:N nano-rods are expected to have potential applications in optic, electronic and optoelectronic devices.

Synthesis, characterization and cathodoluminescence of nanostructured SnO2 using microwave plasma enhanced CVD

Nanostructured tin oxides have been synthesized in the form of nano-pins using SnCl2 ? 2H2O as precursors in a short period of 2.5?min by microwave plasma enhanced CVD. The resulting nano-pins have square cross sections of 50?60?nm at the pin head, 10?20?nm at the pin proper and less than 5?nm at the pin tail; the full length of the pin is about several micrometres. The optical properties measured by cathodoluminescence show strong indigo emission at 404 and 460?nm. The nucleation and growth are dominated by a self-catalytic vapour?liquid?solid mechanism, which has been studied in this work.