Characterization and optical properties of TiO
2
prepared by pulsed laser
deposition
O. Kádár
1
, F. Uherek
1,2
, J. Chlpík
3
, J. Remsa
4
, J. Bruncko
2
, A. Vincze
2
, M. Jelínek
4
1
Department of Microelectronics FEI STU, Ilkoviova 3, 812 19 Bratislava, Slovak Republic
2
International Laser Centre, Ilkoviova 3, 841 04 Bratislava Slovak Republic
3
Department of Physics, FEI STU, Ilkoviova 3, 812 19 Bratislava, Slovak Republic
4
Academy of Science CR, Na Slovance 2, Praha, The Czech Republic
E-mail: ondrej.kadar@stuba.sk
The contribution reports on fabrication and characterization of TiO
2
thin films
on Si substrate. The TiO
2
thin films are used for photonic devices in optical
communication systems. The most important parameter for the waveguide
structures is the refractive index. The crystalline TiO
2
polymorphs can have
different refractive index depending on the structure phase, which is technology
dependent. The waveguide structures was prepared by pulsed laser deposition
using 248 nm KrF laser source and targets of Ti or rutile in oxygen atmosphere.
The optical characterization were done using spectroscopic ellipsometry
providing the information about electron band gap values and determining the
optical parameters (thickness and refractive index) of prepared TiO
2
thin films.
Secondary ion mass spectroscopy (SIMS) and secondary electron microscopy
(SEM) was done to verify the vertical and chemical structure.
1. Introduction
This article is aimed at investigation of optical properties of titanium dioxide (TiO
2
)
waveguide structure prepared by pulsed laser deposition. Titanium dioxide forms three
distinct crystalline polymorphs with corresponding refractive indices – 2,488 (anatase), 2,583
(brookite) and 2,609 (rutile). Rutile has the simplest and best known structure. Anatase and
rutile are both tetragonal, containing six and 12 atoms per unit cell. Each Ti atom is
coordinated to six O atoms and each O atom is coordinated to three Ti atoms. The distortion is
greater in anatase than in rutile. The third form of TiO
2
– brookite shown Fig. 1 (c) has a more
complicated structure. It has eight formula units in the orthorhombic cell. [1]
Fig.1 Crystal structures of TiO
2
(a), Rutile (b), Anastase (c), Brookite [1]
978-1-4244-8575-8/10/$26.00 ©2010 IEEE