The carbon and hydrogen contents in ALD-grown ZnO films define a narrow ALD temperature window. (August 2021)

• Record Type: Journal Article
• Authors: Xia, B.; Ganem, J.J.; Briand, E.; Steydli, S.; Tancrez, H.; Vickridge, I.
• Is Part Of: Vacuum. Volume 190(2021)
• Publication Date: 2021-08
• Subjects: Atomic layer deposition (ALD) -- ZnO thin Films -- Ion beam analysis (IBA); Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2021.110289
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: Zinc oxide thin films grown by atomic layer deposition have been subject to great attention over the past few years. In this work, we study ZnO films grown on Si substrates by atomic layer deposition with di-ethyl zinc (DEZ) as metal precursor and H2 O or D2 O water vapour as oxidant. Film composition as a function of growth temperature is studied by Ion Beam Analysis (IBA) using Rutherford Backscattering Spectrometry (RBS) to determine Zn areal density; Nuclear Reaction Analysis (NRA) for C and O areal density, and Elastic Recoil Detection Analysis (ERDA) for hydrogen areal density. The Zn/O ratio is close to 1 within a broad ALD window consistent with previous studies, however the carbon content varies substantially within this window and is minimum only within a much narrower temperature range. Highlights: We used Ion beam analysis (IBA) to determine the carbon and hydrogen impurity content in ALD ZnO film. Isotopically labelled water (D2 O) revealed that most of the hydrogen in ZnO film comes from DEZ, rather than water oxidant. Combining IBA and ellipsometry, we determined the film density as a function of deposition temperature.