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Effect of annealing temperature on the structure, optical and electronic properties of Tio2 made by thermal treatment of Ti

In this work, TiO2 nanocrystalline thin films were obtained through evaporating Ti films by Electron Beam Deposition (EBD) followed by thermal treatment. The deposition speed of Ti thin fims was carried out at 0.15 nm/s and 1 nm/s. The results show that after annealing at 450˚C for 8 h, the obtained TiO2 thin films have nanoparticle structure with grain size of 20 nm for the Ti thin film deposited at the rate of 1nm/s, whereas at the a deposition rate of 0.15 nm/s, the TiO2 has a nanorod structure with the rod length of 300 – 400 nm. The influence of thermal annealing on structure of TiO2 films have been investigated and indicated that when annealed at 450˚C for 8 hours, all the Ti films were completely oxidized to form TiO2 films with anatase phase. | Communications in Physics, Vol. 24, No. 2 (2014), pp. 155-162 EFFECT OF ANNEALING TEMPERATURE ON THE STRUCTURE, OPTICAL AND ELECTRONIC PROPERTIES OF TiO2 MADE BY THERMAL TREATMENT OF Ti DANG TRAN CHIEN Faculty of Science, Hanoi University of Natural Resources and Environment PHAM DUY LONG Institute of Materials Science, Vietnam Academy of Science and Technology E-mail: dtchien@hunre.edu.vn Received 24 February 2014 Accepted for publication 04 April 2014 Abstract. In this work, TiO2 nanocrystalline thin films were obtained through evaporating Ti films by Electron Beam Deposition (EBD) followed by thermal treatment. The deposition speed of Ti thin fims was carried out at 0.15 nm/s and 1 nm/s. The results show that after annealing at 450˚C for 8 h, the obtained TiO2 thin films have nanoparticle structure with grain size of 20 nm for the Ti thin film deposited at the rate of 1nm/s, whereas at the a deposition rate of 0.15 nm/s, the TiO2 has a nanorod structure with the rod length of 300 – 400 nm. The influence of thermal annealing on structure of TiO2 films have been investigated and indicated that when annealed at 450˚C for 8 hours, all the Ti films were completely oxidized to form TiO2 films with anatase phase. Whereas, at 700˚C the rutile phase was formed. The band gap of TiO2 thin films decreased with annealing temperature in both doposition rate of Ti thin films. The response of the films annealed at 450˚C presented a faster rise and fall in photocurrent under UV illumination on and off interval. Nanoporous structure TiO2 shows photoelectronic property better than that of nanorod structure. The TiO2 films were used in a photo-electrochemical (PEC) cell as a working electrode and a platinum electrode as a counter electrode. The electrolyte solution contains 1 M KCl and 0.1 M Na2 S. Keywords: TiO2 thin films, nanoparticle structure, nanorod structure, photo-electrochemical cell. I. INTRODUCTION Titanium dioxide is a material which has attracted lots of attention