Miniaturized electron-impact-ionization pumps using double-gated isolated vertically aligned carbon nanotube arrays

There is a need for microscale vacuum pumps that can be readily integrated with other MEMS and electronic components at the chip-scale level. Miniaturized ion pumps exhibit favorable scaling down because they are surface-limited and miniaturization increases the ratio between the active surface and the chamber volume, resulting in enhanced ionization and pump rates. Therefore, scaled-down ion pumps are a promising choice for a variety of applications including portable mass spectrometers and sub-mm wavelength vacuum amplifiers. Our micropump architecture consist of a field-emission electron source that is an array of double-gated isolated vertically aligned carbon nanotubes (VA-CNTs), an electronimpact- ionization region, and a non-evaporative ion-implantation getter. Single-gated VA-CNT FEAs were tested as field emitters in high vacuum (10-9 Torr). The current density of the tested device is ~0.5A/cm2 (total current of 0.4mA) and a field enhancement factor of 1.41 x106 V/cm was measured, which is comparable to the simulation results by COMSOL. Two ways to fabricate double-gated VA-CNT FEAs were reported: one has the focus gate in plane with the extractor gate and the other has the focus gate above the extractor gate. Due to problems on fabrication process of double-gated VA-CNTs (short circuit between emitters, extractor gate, and focus gate), we were not able to collect four-terminal measurement, electron-impact-ionization, and pump data. However, procedure on how to collect and analyze field emission data with two gates to find [beta]G and [beta]F was described. In addition, procedures on how to collect and analyze data on electron impact ionization pump were also presented.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2012

Author dc:creator

• Jayanty, Vivi

Advisor dc:contributor.advisor

• Luis Fernando Velásquez-García.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/75659

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/75659