Investigation of post-annealing indium tin oxide for future electro-optical device application

Abstract

The nanostructure transformation associated with electro-optical properties via post-annealing of indium tin oxide film (ITO) is investigated by increasing post-annealing temperature in ambient oxygen. Although oxygen vacancy and activation Sn ions contribute to conductivity of ITO film, the oxygen vacancy inevitably reduces during posting annealing, but Sn-O related bonds are oppositely increased with IR absorption at 790 cm(-1). Moreover, the sheet resistance of as-deposited ITO film 8.6 Omega/sq increases to 47 Omega/sq as the annealing temperature rises to 500 degrees C., the photoluminescence (PL) spectrum indicates that the oxygen vacancy plays a key role in dominating R-s in comparison with Sn-O bonds. The blue light transmittance of ITO film is slightly proportional to the annealing temperature due to phase crystallization enhancing band gap narrowing. Furthermore, as the annealing temperature rises beyond 500 degrees C, the transmittance is compromised between the Burstein-Moss effect of high carrier concentration and nanostructure crystallinity. The oxygen deficient vacancy, instead of Sn-O related bonds, is a major contribution for ITO conductivity and transmittance