Uses of Nanotechnology to Improve Infrared Sensors Joseph 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

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

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

Quantum Dots  A photon counting method of detecting infrared radiation  The quantum dots are generally measured in the single digit nanometers Krishna  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  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 High-sensitivity uncooled microcantilever infrared imaging arrays, edited by F. A. Bjorn, F. F. Gabor and R. N. Paul: SPIE.  Krishna, Sanjay InAs/InGaAs quantum dots-in-a-well photodetectors Infrared Photoelectronics. Warsaw, Poland  Yon, J J, L Biancardini, E Mottin, J L Tissot, and L Letellier Infrared microbolometer sensors and their application in automotive safety. 7th International Conference on Advanced Microsystems for Automotive Applications, May 23, Berlin.  Zhang, Jiangbo, Ning Xi, Hoyin Chan, and Guangyong Li Single carbon nanotube based infrared sensor 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.