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.

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The MWNT-TiO 2 core-shell structures are grown using an ALD method. The as-grown MWNT array is preheated in the ALD reactor chamber at 150 ℃. A TiCl 4 /H 2 O flow is then introduced into the chamber and the flow rate is controlled at 0.25 Å/cycles. After performing the ALD treatment for 200 cycles, uniformly coated TiO 2 layer can be formed on MWNTs, as shown in Figure SI-c and SI-d.