Supersensitive, ultrafast, and broad-band light-harvesting scheme employing carbon nanotube/TiO ₂ core-shell nanowire geometry

We demonstrate a novel, feasible strategy for practical application of one-dimensional photodetectors by integrating a carbon nanotube and TiO ₂ in a core-shell fashion for breaking the compromise between the photogain and the response/recovery speed. Radial Schottky barriers between carbon nanotube cores and TiO ₂ shells and surface states at TiO ₂ shell surface regulate electron transport and also facilitate the separation of photogenerated electrons and holes, leading to ultrahigh photogain (G = 1.4 × 10 ⁴) and the ultrashort response/recovery times (4.3/10.2 ms). Additionally, radial Schottky junction and defect band absorption broaden the detection range (UV-visible). The concept using metallic core oxide-shell geometry with radial Schottky barriers holds potential to pave a new way to realize nanostructured photodetectors for practical use.