Transparent conductive Nb doped TiO2 films prepared by pulsed laser deposition

by Chaojun Wang (MS Candidate)

Wednesday May 16, 2012, 1:30 PM → 2:00 PM Asia/Seoul

119호 (제1과학관)

The 0.5% Nb-doped TiO2 (Nb:TiO2) films were prepared on c-plane sapphire substrates by using pulsed laser deposition at various substrate temperatures, from 350 0C to 750 0C, in vacuum (< 10-5 Torr). X-ray diffraction data suggested that the anatase phase was created below ~550 0C while the rutile phase was stabilized above that temperature. The electrical and optical properties of Nb:TiO2 were largely dependent on the carrier density due to Nb doping or oxygen vacancies rather than its structural phase. In all films deposited in vacuum, the electrical resistivity was a very small value of ~1 m Ohm cm at room temperature and it showed a slight increasing tendency with decreasing temperature. The Hall mobility had a maximum value of 7.3 cm2 /Vs in the rutile phase film made at 650 oC, while the carrier concentration had a maximum value of 1.88 x 1021 cm−3 in the anatase phase film made at 450 oC. The substrate temperature dependence of the optical band gap measured from optical transmittance measurements was very similar to that of the carrier concentration. The properties of 5% Nb-doped TiO2 films on glass substrates which were deposited at room temperature and annealed at varied temperature from 250 ~ 550 oC were also studied.

Thesis Advisor: Prof. Joonghoe Dho