Negative photoconduction of planar heterogeneous random network of ZnO-carbon nanotubes

In this letter, the authors report on the effect of negative photoconduction observed in heterogeneous two-dimensional random networks comprising single-walled nanotubes and ZnO particles, and investigated by room temperature dc-photoconduction measurements. For this, two-terminal thin film devices engineered by solution coating of the nanotubes with ZnO microparticles consistently exhibited increase in the resistance versus decrease in the nanotubes alone with ultraviolet illumination, which is explained within the model of interface-mediated charging/discharging effects. The study suggests the possibility of engineering reduced-cost and multirange nanotube light sensors based on extrinsic carrier modulation via external gating at the interface.