デュアルイオンビームスパッタ法を用いたＡｕ超薄膜の作製とその紫外域透明電極への応用

Abstract

Technologies of fabricating resent semiconductor devices such as electro-luminescence (EL) devices, LED, laser sources and solar cells require conductive films with high transparency to ultraviolet light. Ultrathin Au film is a good candidate for this application, wherein the transparency goes up with a decrease of film thickness. However, it has been known that ultrathin Au films deposited by several methods such as evaporation and conventional sputtering are not conductive due to the formation of island structure at the initial growth stage. In this study, the initial island growth was controlled by Ar bombardment using an ion source, and ultrathin conductive Au films were deposited by dual ion beam sputtering [DIBS]. The optimum condition for the sputtering and Ar bombardment was studied. Again, the two kinds of Au films, without Ar bombardment [IBS], and with Ar bombardment [DIBS], were deposited as a function of thickness (tF). The tF dependence of the morphology and the resistivity (ρ) and the transmittance (T) was investigated. The films deposited by IBS and DIBS transformed from island structure to layer structure at tF of 8.0 and 2.8 nm, respectively. The films showed conductive properties above these critical tF. T of the films was higher than 62% for IBS and 75% for DIBS at a wavelength between 200 and 400 nm. It was found that the technique of Ar bombardment was useful to suppress the initial growth of island structure.