title: The heterojunction effects of TiO2 nanotubes fabricated by atomic layer deposition on photocarrier transportation direction.
abstract: The heterojunction effects of TiO2 nanotubes on photoconductive characteristics were investigated. For ITO/TiO2/Si diodes, the photocurrent is controlled either by the TiO2/Si heterojunction (p-n junction) or the ITO-TiO2 heterojunction (Schottky contact). In the short circuit (approximately 0 V) condition, the TiO2-Si heterojunction dominates the photocarrier transportation direction due to its larger space-charge region and potential gradient. The detailed transition process of the photocarrier direction was investigated with a time-dependent photoresponse study. The results showed that the diode transitioned from TiO2-Si heterojunction-controlled to ITO-TiO2 heterojunction-controlled as we applied biases from approximately 0 to -1 V on the ITO electrode.
authors.affiliation: Department of Materials Science and Engineering, National Chiao Tung University, Hsin-chu, Taiwan, 30010, Republic of China. chih@mail.nctu.edu.tw.
authors.forename: Yung-Huang
authors.initials: YH
authors.lastname: Chang
authors.forename: Chien-Min
authors.initials: CM
authors.lastname: Liu
authors.forename: Chih
authors.initials: C
authors.lastname: Chen
authors.forename: Hsyi-En
authors.initials: HE
authors.lastname: Cheng