The synthesis and fabrication of horizontally aligned single-walled carbon nanotubes suspended across wide trenches for infrared detecting application

摘要

Horizontally aligned single-walled carbon nanotubes (SWNTs) were directly grown across trenches produced on SiO2/Si substrate, forming suspended aligned SWNTs over the trenches, and were fabricated with simple methods for infrared (IR) detection application. The horizontally aligned SWNTs can grow across trenches as wide as 40 mu m. The detector based on such SWNTs shows sharp and remarkable responses to the ON/OFF state changes of the IR lamp and IR radiation with different frequencies. The resistance of the SWNTs decreases about 22.86% under IR radiation with power less than 4 mW. The detector photoresponse to IR radiation of 120 Hz at room temperature could be easily observed. The response time constant is only about 500 mu s, which is more than two orders of magnitude shorter than that of the reported devices based on SWNT films and SWNT-polymer composites. This was achieved due to the absence of intertube junctions in our horizontally aligned SWNTs which exist in SWNT bundles and films and may reduce the signal conduction speed and the IR photoresponse performance. Instead of the bolometric model, the interband transition model is suggested to be the dominating origin of the photoresponse of our SWNT-based detector configuration.