The influence of defects on the surface behavior of TiO2

Kris J. Hameeuw ,  Giovanni Cantele ,  Domenico Ninno ,  Giuseppe Iadonisi 

University of Naples "Federico II", Department of Physics, Piazzale Tecchio, 80, Napoli I-80125, Italy
INFM - Coherentia, Via Cinthia, Napoli 80125, Italy

Abstract

Titanium dioxide is a semiconductor oxide with a wide range of applications. The material is being used as a catalyst, as a gas sensor, as a coating, in ceramics and in electric devices such as a varistor. Recently, TiO2 has also been suggested to replace Si dioxide as a gate insulator in MOSFETs.

In all of these applications, the surface physics of TiO2 plays a major role and is critically influenced by the occurrence of defects. Understanding the surface properties of TiO2 at a fundamental level is considered to be crucial to improve the performance of TiO2 based devices in many fields.

We carried out an exhaustive theoretical study of the technologically most important TiO2 (110) surface, using ab initio techniques. First we will discuss the surface and electronic properties of the clean (110) surface. Next, we will present a detailed analysis of the influence of surface and subsurface defects. These defects consist of missing oxygen atoms in the crystalline structure, the so called oxygen vacancies. We will show that the presence of oxygen vacancies has a strong impact on both the structural and electronic properties. The position of the vacancy in the material alters the way it affects the surface behavior.

This thorough investigation contributes to a deeper understanding of the interaction of TiO2 with other materials. As such, it is a crucial step to grasp the interfacial behavior of this semiconductor oxide. This will be illustrated with the results of a theoretical study of metal atoms on the TiO2 surface that act as a catalyst.

 

Presentation: oral at E-MRS Fall Meeting 2005, Symposium F, by Kris J. Hameeuw
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-30 17:20
Revised:   2009-06-07 00:44