Carbon Nanotube Array for Infrared Detection
Final rept. 1 Jul 2008-30 Jun 2011
BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
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The core effort of this project has been the electrical transport and infrared photoresponse properties of carbon nanotube CNT systems. The word system is important in the context of our work because we have focused on the properties of materials and devices consisting not of a single CNT, but of assemblies with large numbers of CNTs. In these systems it is often not only the properties of single CNTs that count, but also and primarily the way in which they interact with each other and with the other materials comprising the system. Thus a rich interplay between such properties ensues that has been able to generate materials and devices with unprecedented functionality and with rich and interesting electronic properties. Two cases illustrate this. The first is the system that we investigated in the earlier parts of this effort consisting of a macroscopically ordered array of CNTs, all which formed individually electronic-grade heterojuctions with an underlying silicon substrate. This system is comprised essentially of billions of individual CNTs connected in parallel. As such, the properties of individual CNTs were just as important as those of their interaction with each other cross-talk and with the other elements of the system. For example, a few dozens of shorts within this billion or so of parallel diodes could potentially render the device useless. Yet, our development of novel sample fabrication and CNT growth strategies made such shorts a non-issue. This allowed us to demonstrate and study the interesting electrical rectification properties of this CNT-Silicon heterojunction system, and led to the discovery that this system could behave as a broad-band detector of infrared radiation, capable of operating in both cooled and uncooled modes. A further extension of this system was then achieved by loading the interior spaces of the CNTs with other materials of interest, including lead sulfide in both quantum dot and nanowire forms.
- Refractory Fibers
- Infrared Detection and Detectors