Ultraviolet photodetector using pn junction formed by transferrable hollow n-TiO 2 nano-spheres monolayer

We report an ultraviolet (UV) photodetector with a universally transferable monolayer film with ordered hollow TiO spheres on p-GaN. After forming a TiO monolayer film by unidirectional rubbing of hollow TiO spheres on a polydimethylsiloxane (PDMS) supporting plate, we used a 5% polyvinyl alcohol (PVA) aqueous solution to transfer the film onto the target substrate. The PVA/TiO monolayer film was detached from the PDMS film and transferred to the p-GaN/Al O substrate. To investigate the effects of crystallized phases of the TiO hollow spheres, anatase and rutile TiO sphere monolayers prepared by combining template synthesis and thermal treatment. The responsiveness of the UV photodetectors using anatase and rutile hollow n-TiO monolayer/p-GaN was 0.203 A/W at 312 nm and 0.093 A/W at 327 nm, respectively.