Structural Change during Annealing of Amorphous Indium-Tin Oxide Films Deposited by Sputtering with H2O Addition

Abstract
This paper describes the effects of annealing on electric properties and structure of amorphous indium-tin oxide (ITO) films deposited by sputtering at room temperature and with H2O addition. The film resistivity was increased by annealing at 150–200° C; in this temperature range the growth of ITO crystallites dispersed in the amorphous ITO phase was observed. This increased resistivity was found to be due to decreases in both Hall mobility (µ H) and carrier density (n) of the films. Measurements of thermal desorption spectroscopy revealed that two different adsorption states, in terms of H2O molecules which are due to the hydrogen-bonded H2O and OH species, were formed in amorphous ITO films during film deposition and the subsequent annealing process. Factors in the decreases of µ H and n were discussed on the basis of the experimental results obtained.