Ozone oxidation methods for aluminum oxide formation: Application to low-voltage organic transistors

Gupta, S., Hannah, S., Watson, C.P., Šutta, P., Pedersen, R.H., Gadegaard, N. and Gleskova, H. (2015) Ozone oxidation methods for aluminum oxide formation: Application to low-voltage organic transistors. Organic Electronics, 21, pp. 132-137. (doi: 10.1016/j.orgel.2015.03.007)

Abstract

Four atmospheric pressure ozone oxidation methods were used to produce ultra-thin layers of aluminum oxide for organic thin-film transistors. They are UV/ozone oxidation in ambient (UV-AA) and dry (UV-DA) air, UV/ozone oxidation combined with high-voltage discharge-generated ozone in dry air (UV+O3-DA), and discharge-generated ozone in dry air (O3-DA). The lack of the high-energy UV photons during the O3-DA oxidation led to low relative permittivity and high leakage current density of the AlOx layer that rendered this method unsuitable for transistor dielectrics. Although this oxidation method led to the incorporation of oxygen into the film, the FTIR confirmed an increased concentration of the subsurface oxygen while the XPS showed the highest portion of the unoxidized Al among all four methods. The remaining three oxidation methods produced AlOx films with thicknesses in excess of 7 nm (2-h oxidation time), relative permittivity between 6.61 and 7.25, and leakage current density of (1–7) × 10−7 A/cm2 at 2 MV/cm, and were successfully implemented into organic thin-film transistors based on pentacene and DNTT. The presence of –OH groups in all oxides is below the detection limit, while some carbon impurities appear to be incorporated.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Pedersen, Mr Rasmus and Gadegaard, Professor Nikolaj
• Authors: Gupta, S., Hannah, S., Watson, C.P., Šutta, P., Pedersen, R.H., Gadegaard, N., and Gleskova, H.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: Organic Electronics
• Publisher: Elsevier
• ISSN: 1566-1199
• ISSN (Online): 1878-5530
• Copyright Holders: Copyright © 2015 The Authors
• First Published: First published in Organic Electronics 21:132-137
• Publisher Policy: Reproduced under a Creative Commons License