Transcript Uses of Nanotechnology to Improve Infrared Sensors

Uses of Nanotechnology to
Improve Infrared Sensors
Joseph Dvorak
ECEN 5060 – Fundamentals of
Nanotechnology
Oklahoma State University
Introduction
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Current state of infrared technologies
Quick overview of infrared theory
Nanotechnology’s contributions to improve
infrared sensors
The future of infrared sensors and
nanotechnology
Infrared Overview
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Infrared radiation is the region of the electromagnetic spectrum
from 720nm to 1000μm and includes the radiation naturally
emitted by objects at room temperature.
It has long been used by the military, although recently
commercial and industrial uses have begun to appear.
Main limitations are the necessary trade-offs between
 cost
 bulky and complex equipment
 response time
 image quality
 sensitivity
Infrared Theory
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Planck’s Law
Eb , 
2c 2 h5
e
ch
 T
1
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Electrical resistance dependent on
Temperature
Thermal Expansion
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Photon Capture
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 T  TL
Solutions from Nanotechnology
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Thermal Approaches
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Microbolometers
Microcantilevers
Quantum Approaches
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Quantum Dots
Carbon Nanotube-Based Devices
Microbolometers
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Infrared Radiation causes a
temperature change in the
suspended plate which changes
its electrical resistance.
Essentially a larger scale object
that after undergoing many size
reductions is in the nanoscale.
To maintain thermal isolation of
the plate, the sensor must be
packaged in a vacuum and
maintained at that vacuum.
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One of the most advanced
infrared detectors to use
nanotechnology as they are
already on the market.
In the future, feature size
reductions are expected.
Yon et al. 2003.
Microcantilevers
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A thermal infrared detector that utilizes different rate
of expansion for different materials
Device is measured in micrometers, but feature sizes
are in the nanometer range
Currently under development
Hunter et al. 2006.
Quantum Dots
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A photon counting method of detecting infrared radiation
The quantum dots are generally measured in the single digit
nanometers
 Quantum dots are small
enough that size begins to
dictate electrical properties
 Can trap an electron in three
dimensions to improve
sensitivity
 Much current work is focused
on quantum dots in a
quantum well
Krishna. 2005.
Carbon Nanotube-Based Devices
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Photon detection method for sensing infrared radiation that
utilizes carbon nanotubes
Since the characteristics of carbon nanotubes can change with
diameter and angle of carbon atom pattern, picking certain
values makes the carbon nanotube sensitive to infrared
radiation
The size of a carbon nanotube, only allows the electron to
travel in one dimension making carbon nanotubes very useful
for implementing across contacts
Still in the very early stages of
development
Zhang et al. 2006.
Future Possibilities
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Low cost, room temperature, simple infrared
detectors based on nanotechnology will find
many uses
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Automotive Safety and Control
Industrial and Construction safety
Industrial Process Control
Security Systems
Conclusion
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The widespread adoption of infrared systems will
require several improvements
Two primary methods exist to detect infrared
radiation
Nanotechnology has the potential to improve
infrared technologies in several ways, including the
four mentioned here
Solving these challenges in infrared sensing systems
can result in applications that will greatly improve
peoples’ lives and/or safety
Image References
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Hunter, Scott R., Gregory Maurer, Lijun Jiang, and Gregory Simelgor.
2006. High-sensitivity uncooled microcantilever infrared imaging arrays,
edited by F. A. Bjorn, F. F. Gabor and R. N. Paul: SPIE.
Krishna, Sanjay. 2005. InAs/InGaAs quantum dots-in-a-well
photodetectors. 5957. Infrared Photoelectronics. Warsaw, Poland
Yon, J J, L Biancardini, E Mottin, J L Tissot, and L Letellier. 2003.
Infrared microbolometer sensors and their application in automotive
safety. 7th International Conference on Advanced Microsystems for
Automotive Applications, May 23, 2003. Berlin.
Zhang, Jiangbo, Ning Xi, Hoyin Chan, and Guangyong Li. 2006. Single
carbon nanotube based infrared sensor. 6395. Electro-Optical and
Infrared Systems: Technology and Applications III. Stockholm, Sweden.
Other references for the topics listed here are included in the associated
paper to this presentation. They have been omitted here to save space.