Oxygen-deficient indium tin oxide thin films annealed by atmospheric pressure plasma jets with/without air-quenching

This paper reports the experimental results of oxygen-deficient ITO thin films annealed by atmospheric pressure plasma jets (APPJs) with and without air-quenching. The as-deposited oxygen-deficient ITO thin films are dark in color and gradually become transparent after N-2 APPJ treatment. Quartz tubes with and without side holes are installed downstream of the APPJ to control the introduction of air into the plasma jets. Air-quenching reduces the plasma jet temperature from 580 to 385 degrees C but enhances the reactivity and renders faster conversion of dark ITO to transparent ITO despite the lower plasma jet temperature. With air-quenching, the transmittance (lambda = 550 nm) of a 100-nm-thick ITO thin film on glass substrate reaches 87% after 90s of APPJ treatment, compared to 7.2% in the case of the as-deposited ITO thin film. The resistivity decreases dramatically from 1.81 x 10(-2) to 8.58 x 10(-4) Omega cm after 15s of APPJ treatment with air-quenching owing to crystallization and oxidation processes that reduce the defect density in the material. Subsequently, the resistivity increases slightly to 1.71 x 10(-3) Omega cm after 90s of APPJ treatment with air-quenching because of the reaction of oxygen and ITO that reduces the oxygen vacancies. Our results demonstrate that APPJ treatment can be used as a rapid thermal annealing process for ITO thin films. (C) 2013 Elsevier B.V. All rights reserved.