K. Yokoo

A monolithic field emitter array with a JFET

This paper proposes a novel structure of the conical Si field emitters monolithically incorporating a vertical-type junction field effect transistor (JFET) and demonstrates the emission control in field emission from the emitters. The proposal has many attractive advantages in the display application and reliable fabrication, because the structure needs neither additional area for the JFET nor additional process except ion implantation. The experimental results of the emitters show excellent controllability and stability in the emission current.

Electron emission from porous silicon planar emitters

Porous silicon planar emitters were fabricated by depositing a thin Au film on a conventional porous Si and their emission characteristics were examined. The emission currents and energy distributions were measured for the emitters with various Au thicknesses and for cesiated ones. The experimental results suggest that the emission mechanism of the porous silicon emitter studied in this work is conventional field emission, in which electrons are emitted from nanocrystals in the porous silicon directly into a vacuum.

Field emission from porous (100) GaP with modified morphology

Morphology of n-type porous GaP samples with (100) crystal orientation was modified by postchemical etching for field-emitter application. The structures produced have uniform size and shape distribution and are found to show good emission characteristics. The mechanism of the morphology modification is explained, and a strong correlation between field-emission characteristics and postchemical etching time is shown.

Carbon Nanotube on a Si Tip for Electron Field Emitter

In this letter, the results of selective growth and electron field emission characterization of an individual carbon nanotube on a Si tip are presented. An individual, multiwall carbon nanotube was grown vertically at the apex of a microfabricated Si tip using hot-filament chemical vapor deposition with a mixture of C2H2 and H2 gases. During the growth process, an electrical filed of 5×104 V/m was applied between the Si tip and a filament to electrically enhance the growth of the carbon nanotube from the apex of the tip. The carbon nanotube with a diameter of 4–25 nm and a length of 300–400 nm was vertically aligned from the apex of the Si tip. Electron field emission characteristics of the single Si tip with and without the individual carbon nanotube on the same substrate were measured at room temperature in a vacuum of 1.7×10-4 Pa. The threshold voltages were approximately 40 V (4 V/µm) and 200 V (20 V/µm) for the Si tips with and without the carbon nanotube, respectively.

Emission characteristics of a GaAs wedge emitter monolithically fabricated with an air bridge and a cantilever anode

GaAs wedge emitters with an air bridge anode and a cantilever anode were monolithically fabricated using a micromachining technique. The threshold voltage of electron emission is about 8 V for the diode between the emitter and the air bridge anode, while only 1.5 V for the diode between the emitter and the cantilever anode. The current–voltage characteristic of the air bridge diode is due to a field emission, on the other hand, that of the cantilever diode is recognized as a direct tunneling of electrons through the reduced air gap between the emitter and the cantilever by electrostatic force.

Fabrication of a GaAs emitter with a high aspect ratio for generation of prebunched electron beam using Gunn effect

The fabrication process-flowchart of the GaAs emitter with a high aspect ratio is examined. The starting material is a GaAs epitaxially-grown wafer consisting of a n/sup +/-GaAs cap layer, a n-GaAs active layer and a n/sup +/-GaAs substrate. Firstly a double layer mask consisting of a SiO/sub 2/ layer and a resist layer was formed. Then isotropic etching in H/sub 2/SO/sub 4/-H/sub 2/O/sub 2/-H/sub 2/O solution and vertical reactive ion etching in Cl/sub 2/ plasma took place, followed by a final wet etch to form a sharp tip. The emission characteristics of the emitter thus formed were recorded.

Growth of a sub-micron single diamond particle on a Si tip and its field emission characteristic

Diamond has been receiving a great deal of attention as a high electron emission material due to an expectation of a negative electron affinity or a low work function. However, the emission mechanism from the diamond is still unclear. To identify the emission sites, we grew a sub-micron single diamond particle on the top of a single Si tip.

Emission characteristics of a gallium arsenide wedge emitter monolithically fabricated with an air bridge and a cantilever anode

GaAs wedge emitters with an air bridge and a cantilever anode were monolithically fabricated using a micromachining technique. The threshold voltage of electron emission is about 8 V for the air bridge emitter, while only 1.5 V for the cantilever emitter. The current-voltage characteristic of the air bridge emitter is due to a field emission, while that of the cantilever emitter is recognized as direct tunneling of electrons through the reduction of the air gap between the emitter and cantilever by electrostatic force.