Small diameter TiO2 nanotubes with enhanced photoresponsivity

We report ultraviolet (UV) light detection of thin wall TiO2 nanotubes (TNTs) with open diameter ~ 20 nm obtained by a two anodization procedure. This small diameter nanotubular geometry shows significant enhancement of the photoresponsivity and results in a large increase of photocurrent. The photocurrent is one order higher than that of classical nanotubes with diameter of 140 nm at − 1.0 V bias. We attribute this improvement to the modulation of hole carrier density as a result of field effects from the diameter-dependent population of the surface-trapped electrons. This finding demonstrates inherent size effects of internal gain in semiconductor nanotubes.

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► Small diameter TiO2 naotubes with thin wall by a two anodization step
► Inherent size effects of internal gain in semiconductor nanotubes
► Integration of nanomaterials into optoelectronics