High Quality Oxide Films Deposited at Room Temperature by Ion Beam Sputtering

Abstract

We have deposited dense and pinhole-free thin films of SiO₂, Al₂O₃ and ITO at room temperature via ion beam sputtering. The SiO₂ films were found to be of similar quality as thermal oxide with a resistivity greater than 10¹⁵ Ω·cm and breakdown field in excess of 7 MV/cm. The Al₂O₃ films were part of a Pt- Al₂O₃-Pt vertical tunnel junction and were kept extremely thin, from 2 nm to 4 nm. The current-voltage characteristics of these junctions indicated a breakdown field in excess of 20 MV/cm, roughly twice that achieved by ALD films. This breakdown voltage was found to be independent of junction area, strongly suggesting the absence of pinholes in the film. The ITO films were 50 nm to 100 nm thick. As deposited, they are fully transparent with an electrical resistivity of 5x10^-4 Ω·cm.