A novel photodetector based on double-walled carbon nanotube （DWCNT） film/TiO2 nanotube array （TNA） heterojunctions was fabricated, which exhibited high photoresponse in a broad spectral range. The photoresponse of the detector was dramatically dependent on the length of the TNAs. High photocurrent-to-dark current ratio with a value of 3360 was observed in the visible range by optimizing the lengths of the TNAs. The photosensitive regions could be extended into the near-infrared range. These results reveal that DWCNT film/TNA heterojunctions show potential applications for broad band photodetectors.
