Uses of Nanotechnology to Improve Infrared SensorsJoseph Dvorak

ECEN 5060 – Fundamentals of Nanotechnology

Oklahoma State University

Introduction 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 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 Planck’s Law

Electrical resistance dependent on Temperature

Thermal Expansion

Photon Capture

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Solutions from Nanotechnology Thermal Approaches

Microbolometers Microcantilevers

Quantum Approaches Quantum Dots Carbon Nanotube-Based Devices

Microbolometers 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.

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 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 A photon counting method of detecting infrared radiation The quantum dots are generally measured in the single digit

nanometers

Krishna. 2005.

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

Carbon Nanotube-Based Devices 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

Zhang et al. 2006.

Still in the very early stages of development

Future Possibilities Low cost, room temperature, simple infrared

detectors based on nanotechnology will find many uses Automotive Safety and Control Industrial and Construction safety Industrial Process Control Security Systems

Conclusion 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 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.