Si JFET-Controlled Carbon Nanotube Field Emitter Arrays

1
Si JFET-Controlled Carbon Nanotube Field Emitter
Arrays
Qiong Shui1, Martin Gundersen1,2, Ryan J.
Umstattd3, Chongwu Zhou2, Alan M. Cassel4,
lJonathan Shaw5, and David S. Y. Hsu5 1Department
of Chemical Engineering and Materials
Science,University of Southern California, Los
Angeles, CA, 90089-0271 2Department of
Electrical Engineering Electrophysics,University
of Southern California, Los Angeles, CA,
90089-0271 3Physics Department, Naval
Postgraduate School, Monterey, CA, 93943 4Center
for Nanotechnology, NASA Ames Research Center,
Moffett Field, CA, 94035 5Naval Research
Laboratory, Washington, DC, 20375
Introduction
Measurements
Fabrication Process

• Motivation
• 1. The introduction of Spindt microtip 1 cold
  cathodes has led to great interest in the pursuit
  of electron beam sources for flat panel display
  and vacuum microelectronic devices
• 2. CNTs are the closest one that have ideal
  field emitters2
• Stable at high temperature
• Have high electrical and thermal conductivity
• Exhibit ballistic electron transport.
• 3. Stability and lifetime are two important
  issues to be addressed before field emitters find
  wide applications
• Active devices, JFETs, were proposed in our study
  to control the stability of the emission current
  of CNTs

Fig. 5 Leakage current vs. the voltage between
the extraction gate and the control gate. The
thickness of SiO2 is 1 ?m. the calculated
resistivity of our deposited SiO2 at 25 C is
about 6?1012 O-cm.
CNTs Field Emitter Applications 1. Providing the
electron beam(s) inside of flat panel field
emission displays(FED) 3
Fig. 6 SEM image shows the structure after Cr and
SiO2 were etched through the patterned 2 ?m
diameter emitter sites

• lower power consumption
• Wider view angles
• Viewable from any angle with no change in
  brightness, contrast or color
• Faster response time

2. Providing the electron beam in vacuum
microwave amplifiers/oscillators 3. Providing the
electron beam for charge neutralization when
using ion thrusters for propulsion in space
Simulation Results for Si JFETs
Fig. 7 SEM images(left and right) of vertically
aligned CNTs grown on Si post JFETs. The tilt
angle for taking the images is 85 .
Future Work

• Test the emission current of CNT emitter arrays
  and its stability
• Optimize the fabrication process

The left figure (Fig. 1) shows Si post JFET
structure for simulation of breakdown voltages of
JFETs. The right figure (Fig. 2) shows the
breakdown voltage of the JFETs when ion
implantation energy are at 150 keV and 200 keV,
respectively
References
Acknowledgement
1. C. A. Spindt, "A thin-film field-emission
cathode," J. Appl. Phys., vol. 39, pp. 3504-3505,
1968. 2. T. Utsumi, "Keynote address vacuum
microelectronics What's new and exciting," IEEE
Transaction on Electron Devices, vol. 38, pp.
2276-2283, 1991. 3. http//other.nrl.navy.mil/CREB
WorkShop/Jensen.pdf
The Pulsed Power Group of USC thanks the Air
Force Office of Scientific Research for their
generous support.
Fig. 3 Boron impurity distribution in Si
simulated by SRIM-2003 at an ion implantation
energy of 150keV and a dose of 5?1015/cm3.
Fig. 4 Drain Voltage vs. Id for the built-in JFET
at different Vgs.