Fu-Gow Tarntair

Field emission properties of two-layer structured SiCN films

Abstract The electron emission characteristics of two-layer structured silicon carbon nitride (SiCN) films, which were composed of amorphous and nanocrystalline phases, were studied. Rutherford backscattering spectroscopy (RBS) was used to determine the composition of the SiCN film. The ratio (Si;C)/N of the SiCN film was kept at approximately 0.75, which is identical to that of Si 3 N 4 film. High resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to investigate the bonding structures of the SiCN films. In comparison with silicon nitride films, the turn-on voltage (for an emission current of 0.01 mA/cm 2 ) of the SiCN films was lower and the emission current densities of the SiCN significantly enhanced. The promising emission properties of the SiCN film could be due to the unique two-layer structure wherein nanocrystalline SiCN was grown on top of the amorphous interlayer with sp 2 CN bond in the SiCN film.

Fabrication and Characterization of Carbon Nanotube Triodes

To achieve high emission current density, carbon nanotube triodes have been proposed using recessed oxide as the insulator between the gate and the carbon nanotubes to replace the conventional spacer. An anode current of 10 µA was achieved with a gate voltage of 98 V for a nanotube sample prepared with a growth time of 12 min. Carbon nanotubes synthesized with various growth times were analyzed using a scanning electron microscope and Raman spectroscopy. By increasing the growth time, longer carbon nanotubes were obtained. Effects of the length of the carbon nanotubes on the field emission of the triodes are discussed. Enhanced luminance was obtained as the anode voltage increased from 600 V to 1000 V. Such carbon nanotube triodes are promising for utilization in future field-emission displays.

Thin-Film Transistors with Polycrystalline Silicon Films Prepared by Two-Step Rapid Thermal Annealing

A novel two-step rapid thermal annealing (RTA) process has been developed to significantly reduce the crystallization time for the solid-phase crystallization (SPC) of amorphous silicon films. In comparison with the conventional SPC processes, it not only keeps a low thermal budget but also achieves a larger poly-Si film grain size than that obtained by one-step RTA, and even as large as that obtained by conventional furnace annealing (CFA). Furthermore, poly-Si thin-film transistors fabricated by such a novel annealing scheme possess electrical characteristics superior to those obtained by one-step RTA and comparable to those obtained by long-time CFA.

Field-Emission Properties of Aligned Carbon Nanotubes

Dense, well-separated, and aligned carbon nanotubes have been prepared via bias-enhanced microwave plasma chemical vapor deposition. The turn-on fields defined at the emission current density of 10 µA/cm2 are about 3.35 V/µm, 2.54 V/µm, and 3.54 V/µm, for the immersion times in PdCl2 of 1 min, 20 min, and 40 min, respectively. The corresponding emission current densities are about 0.97 mA/cm2, 4.5 mA/cm2, and 0.44 mA/cm2 at the electric field of 5 V/µm. The higher emission current obtained from the aligned carbon nanotubes for the immersion time of 20 min is ascribed to the denser and sharper nanotubes formed in this condition.

Enhanced electron emission from phosphorus- and boron-doped diamond-clad Si field emitter arrays

Abstract A new fabrication technology of polycrystalline diamond-clad Si microtips using microwave plasma chemical vapor deposition (MPCVD) has been developed to improve the characteristics of electron field emission from the pure Si tips. A uniform and smooth coaling morphology for the diamond-clad Si tips have been achieved. Electron emission currents of diamond-clad tips are much higher than those of pure Si tips. Such great improvement is attributed to the lowering of the effective work function in the diamond-clad tips. The effects of phosphorus- and borron-doped diamond-clad Si tips have been also studied in comparison with the undoped ones. The current-voltage characteristics of the undoped diamond-clad tips were further enhanced by the in-situ doping of phosphorus or boron due to a higher electron supplement. Moreover, the P-doped diamond-clad tips show a better field emission performance as compared to the B-doped ones. This difference is surmised to be associated with the higher electron conductivity and defect densities of P-doped diamond films.

Fabrication and Characterization of Various Carbon-Clad Silicon Microtips with Ultra-Small Tip Radii.

Various types of ultra sharp Si microtips and multitips with carbon-clading films were fabricated by microwave plasma chemical vapor deposition (MPCVD). The radii of these Si tips prepared by bias assisted carburization (BAC) can be reduced below 300 A under a low deposition temperature (<550°C). Field emission characterization was performed in a high vacuum environment. With an applied anode voltage of 1100 V, emission currents of 169 µA, 198 µA, and 385 µA can be achieved from an array of 50×50 BAC-clad Si monotips, Si multitips via high bias, and Si multitips via the Ar presputtering technique, respectively. Both the auger electron spectroscopy (AES) and X-ray photo-electron spectroscopy (XPS) studies of the C 1 s peak suggest that the BAC-cladding is more likely to be a carbon-rich SiC layer or a SiC layer mixed with a small amount of diamond nuclei. This BAC-carbon can be used as an effective nucleation layer for further diamond nuclei. Due to the low field emission, low temperature, and large area growth capability, the sharp BAC-clad Si multitip field emitter arrays are attractive for flat panel display applications.