Surface characteristics of indium tin oxide deposited by facing target sputtering and its effect on the performance of organic light emitting diode

Abstract

A new facing target sputtering (FTS) method that has two facing targets and substrate locates vertically to the targets was used for ITO anode deposition in OLED. The ITO different from it by a conventional DC or RF magnetron sputtering was optimized in crystallinity, grain morphology, surface roughness and oxygen content by plasma treatment, and the effect on the OLED I– V characteristic was identified. Crystallinity of ITO was improved with a short plasma treatment time less than 15 min. The grains were an equi-axed as deposited state and changed to columnar grains when the plasma treatment time was exceeded above 20 min. The surface roughness was maintained within the targeted 1.8–2.0 nm range with plasma treatment from 5 to 20 min. Oxygen content measured using XPS analysis was increased with 15 min plasma treatment during the ITO grains maintained an equi-axed, but it was decreased again with 25 min plasma treatment. The I– V characteristic of OLED was relatively good with 15 min plasma treatment. It was considered because the ITO anode can contain higher oxygen in equi-axed grains, and can have better crystallinity and relevant surface roughness by 15 min plasma treatment.