Effects of the variations of oxide structure on the electrical and optical properties of ITO films

Abstract

In the paper, conductive and transparent indium tin oxide (ITO) films have been prepared by reactive magnetron sputtering using powder target of In<SUB>2</SUB>O<SUB>3</SUB> with 10wt% SnO<SUB>2</SUB> in an Ar/O<SUB>2</SUB> atmosphere. The structural, composition, optical and electrical properties of the films deposited at different substrate temperature (150 approximately 350 degrees Celsius) have been investigated. Some interesting results obtained in this work, which might be somewhat new, are that the variations of oxide structure and concentration greatly influence the electrical properties of ITO films. X-ray diffraction patterns and X-ray photoelectron spectroscopy (XPS) show that the films deposited at substrate temperature 250 degrees Celsius or more are consist of In<SUB>2</SUB>SnO<SUB>5</SUB> and In<SUB>2</SUB>O<SUB>3</SUB> with no Sn<SUB>3</SUB>O<SUB>4</SUB>. When substrate temperature is lowered to 150 degrees Celsius, Sn<SUB>3</SUB>O<SUB>4</SUB> occurs besides In<SUB>2</SUB>O<SUB>3</SUB> in the films. The above result indicates the occurrence of Sn<SUB>3</SUB>O<SUB>4</SUB> is unfavorable to the conductive properties. When substrate temperature is increased, Sn<SUB>3</SUB>O<SUB>4</SUB> disappears, and oxygen vacancy and the electron donor Sn<SUP>+4</SUP> concentration are increase, which result in a great improvement of the electrical and optical properties.