Abstract
Single-wall carbon nanotube (SWCNT)/n-type silicon (n-Si) heterojunctions with a high photoresponsivity are considered promising for use in photodetectors. However, the performance of large-area SWCNT film/n-Si heterojunction-based photodetectors has been much lower than that fabricated using isolated SWCNTs, where the efficient assembly of SWCNT networks with the desired structure is a key issue. In this study, we prepared a small-bundled SWCNT (SB-SWCNT) film with a carbon-welding structure at tube-tube junctions, which greatly decreased the contact resistance and improved the work function. The fabricated SB-SWCNT film/n-Si heterojunction-based photodetectors showed a very high detectability of 4.2 x 10(13) Jones for an 890 nm laser with 0 bias, much higher than that of commercial photodetectors. The detectors also demonstrated good stability with a 97% R value retained after being exposed in air for 30 days, and a broad spectral response (540-1090 nm).