N. Ghosh

A monolithic multi-finger nanodiamond lateral vacuum microtriode

This article reports a vacuum multi-finger monolithic microtriode utilizing nanodiamond as the emitting material. The structure is comprised of 140-fingerlike nanodiamond emitters with built-in nanodiamond gate and Si anode. A mixed lithography patterning approach is used to fabricate the three-terminal device structure. Triode characteristics, demonstrating gate controlled emission current modulation at low operating gate and anode voltages, are obtained. The realization of the efficient monolithic microtriode allows further development of robust vacuum integrated circuit for application in high temperature and radiation harsh environments.

Nanodiamond vacuum field emission integrated devices

The superb material properties of nanocrystalline diamond (nanodiamond) materials coupled with practical chemical vapor deposition (CVD) processing of deposited nitrogen-incorporated nanodiamond on variety of substrates, have promoted further interest in the use of these diamond-derived materials as electron field emitters. Experimentally, nanodiamond emitters have been observed to emit electrons at relatively low electric fields and generate useful current densities. In this work, recent development in nanodiamond vacuum field emission integrated electronic devices, viz., the nanodiamond triodes, transistors and integrated differential amplifiers are examined. The material properties, device structure and fabrication process, and the electrical performance of these devices are presented.

9.5: Resonant tunneling and extreme brightness from diamond field emitters and carbon nanotubes

We report new results from field emission microscopy studies of multi-wall carbon nanotubes and from energy-spectrum measurements of beams from diamond field emitters. In both systems, we find that resonant tunneling through adsorbed species on the emitter surface is an important and sometimes dominant effect. For diamond emitters our observations include order of magnitude emission enhancement without spectral broadening, complex spectral structure, and sensitivity of that structure to the applied electric field. For carbon nanotubes we have observed electron beams from individual adsorbates which approach the maximum beam brightness allowed by Pauli exclusion.

9.4: The effect of ballast resistor and field screening on electron emission of nano-diamond emitters fabricated on micropatterned silicon pillar arrays

This paper describes the influence of ballast resistor and field screening on the electron field emission behavior of nano-diamond emitter arrays fabricated on micropatterned silicon pillars. Arrays of 50×50 silicon pillars with different ballast resistances, pillar separations, capped with nano-diamond, have been fabricated on different silicon substrates as cathode for field emission testing. The goal of this study is to evaluate the fabrication method and electron emission characteristics in this configuration for field emission applications. The electron field emission results have been compared to observe the effect of the ballast resistive behavior and array spacing of micropatterned silicon pillars on the nano-diamond field emission behaviors.

A miniaturized power source using electron stimulated impact ionization field emission

This paper reports the fabrication and characterization of miniaturized monolithic lateral field emission power cell (FEPC) comprising of carbon nanotube (CNT) emitters and an integrated metallic anode. Electron stimulation impact ionization on FEPC CNT cathode was activated by an integrated electron beam emitter. Field emission behavior with and without the activation of the electron beam was characterized in diode configuration. The emission current of the FEPC increased with the activation of the electron beam. At this operating condition, ten times current amplification and 1.4 μW of power was generated. Results demonstrate the feasibility of power generation using electron stimulated impact ionization.

Diamond field emission arrays (DFEAs) for high-power free electron lasers

Compared to the present prevalent use of photocathodes for free-electron lasers (FELs), the field-emitter array (FEAs) possesses several advantages as an electron source, namely, high brightness, ruggedness, no drive laser requirement and minimal heat generation. And, compared to Spindt-type molybdenum (Mo) and silicon-tips FEAs, diamond FEAs (DFEAs) have strong carbon-carbon covalent bonding (high activation energy for electromigration), are chemically inert, mechanically and thermally stable, with a low sputter coefficient (resistant to bombardment of positive ions) and low electron affinity for efficient electron emission.

Nano-diamond ridge structure emission arrays capped on micro-patterned silicon pillars

CVD nano-diamond structures are interesting electron emitters because of their superior electronic properties and tolerance to operate at much higher temperatures and harsh environments [1]. Other advantages of nano-diamond as emitters include chemical and electrical stability, high breakdown voltage, low turn-on electric field and excellent thermal conductivity [1]. In this paper, we report the fabrication and observation of electron field emission from an array nano-diamond ridge structure capped on micropatterned silicon pillars.