Photonic Effect on Oxygen-Doped and De-Doped Carbon Nanotubes

We present a thermal annealing method to control oxygen doping in carbon nanotube (CNT) based infrared (IR) detector. CNTs have been found to be sensitive under near IR radiation and they could be used as IR sensing elements. When a CNT is manipulated between two metal electrodes, two Schottky barriers are formed at the CNT-metal interfaces. The Schottky barriers play an important role in IR detection. However, oxygen absorption of a CNT changes the electronic properties of the CNT, resulting Schottky contacts and contact resistances are changed. The influence of oxygen removed CNT was studied by a thermal annealing process. Our experimental results showed that photocurrent and dark current of the CNT based IR detectors were changed after the thermal annealing process. Parylene C thin film was also coated on the detector, it isolated the detector from the ambient environment and prevented oxygen absorption of the CNT again. The parylene C packaged CNT based IR detector was fabricated and tested under near IR radiation. Current results indicated that the CNT based IR detector coated with parylene C was capable of sensing IR radiation and exhibited repeatable responses. Therefore, the annealing process and the packaging process are important processes to control oxygen doping of a CNT. As a result, the CNT based IR detectors can be fabricated with high efficiency, high sensitivity, stable and reliable performance.