Takahito Ono

Development of monolithic PZT microstage for the application of ultra high-density data storage

The paper presents the fabrication and characterizations of a compact PZT actuated microstage with multi degrees of freedom (DOFs). The entire device is fabricated in a symmetrical arrangement from a monolithic PZT plate of size 15/spl times/15/spl times/0.8 mm/sup 3/. Displacement amplification mechanisms are integrated in the structure to increase the stroke of the PZT actuator. The performances of the displacement and the resonant frequencies are simulated using a finite element method (FEM). Simulation results show the possibility of achieving a displacement of 8 /spl mu/m in x- and y-axes and 10 /spl mu/m in z-axis under the applied voltage of 100 V. A prototype has been fabricated and evaluated. The FEM simulation and experimental results are compared.

Schottky emitters with carbon nanotubes as electron source

In this paper we present a simple approach for making a Schottky emitter with carbon nanotubes (CNT). A tungsten wire of 0.3 mm diameter was used as a heating filament. An iron rod of 0.3 mm diameter having a sharp tip was weld-bonded to the filament. By heating the filament to around 750/spl deg/C in a mixture of (C/sub 2/H/sub 2/+Ar), multi-wall CNT was grown at the Fe tip. Electron field emission and thermal-field emission properties of the fabricated Schottky emitter were measured at different temperatures. At room temperature, the field emission current well obeyed the Fowler-Nordheim (F-N) mechanism with threshold voltage of around 0.2 V//spl mu/m. At the temperature of higher than 780/spl deg/C, the thermal-field emission dominated and both field emission and thermal-field emission were very stable with very low fluctuation. Enhancement factor of 1.3 /spl times/ 10/sup 7/ m/sup -1/ and work function of 4.95 eV were evaluated for the grown CNT. The mentioned CNT-Schottky emitters for advanced electron beam instruments are expected.

Carbon nanotube integrated on silicon tips for electron field emitter: tip apex patterning and emission characterization

In this work, we developed a selective patterning and lift-off technique for synthesis and patterning of carbon nanotube (CNT) at the apex of a silicon tip. Purpose of this work is to improve the throughput and yield rate of forming CNT at the silicon tip as electron field emitters. The sharp silicon micro-tip were formed by an ICP-RIE dry etching and wet etching in a TMAH solution. After thermally oxidation at 950/spl deg/C and selective etching in a buffer-HF (BHF) solution, a sharp silicon tip was formed at the center of a small silicon oxide aperture. CNTs were entirely grown over the tip by a Hot Filament-Chemical Vapor Deposition (HF-CVD) using Fe as a catalyst. After removing of the sacrificial silicon oxide layer in the BHF solution, small size CNTs bundles were remained at the apex of the silicon tip. The emission properties of the grown individual and bundle CNT at the Si tip were measured, and compared with a single silicon tip. The threshold voltage of the individual CNT was found to be 4V//spl mu/m, that is 5 times lower than that of the silicon tip. Emission pattern of the bundle CNT/Si tip was observed using a phosphor anode screen (ZnO, Zn).