Carbon Nanotube Array for Infrared Detection

We explore the basic science issues and device potential of our carbon nanotube-silicon (CNT-Si) heretorjunctions for infrared photodetection. We focus on the underlying mechanism of infrared photocurrent response, which is elucidated by a detailed study of the dependence of the photocurrent on modulation frequency and intensity of the incident infrared radiation. The photocurrent generation is ascribed to the formation of the CNT-Si heterojunction, rather than the thermal gradient in the structure. The potential detectivity of the CNT photodiode is evaluated by considering the Auger recombination rate limit and found to be several thousand times greater than HgCdTe. The infrared photo-detection capability of the CNT-Si heterojunction is demonstrated by a comparison between the experimental photo-responses from Si and the carbon nanotubes. With the help of analytical formulas and simulation tools, we also investigate the temperature dependence of the 1D-3D heterodimensional CNT-Si heterojunction. These findings establish a basic understanding of this unique hetero-dimensional junction system and will help guide further development, design, and optimization. NOTE: As ofNovember 2008 the remaining options for thi s grant will not b e exerci sed and our sponsored programs office wi ll initiate the grant c loseout procedures.