Atomic Layer deposition of iron oxide nanotubes

Mårten Rooth 1Anders Hårsta 1Anders Johansson Mats Boman Kaupo Kukli Jaan Aarik 2

1. Uppsala University, Department of Materials Chemistry, Angstrom Laboratory, Uppsala, Sweden
2. Institute of Physics, University of Tartu, Riia str. 142, Tartu 51014, Estonia

Abstract

Iron oxide is a material of great interest in numerous scientific fields and applications. Amongst the many applications and properties of this material photo catalysis, gas sensors and the interesting magnetic behaviour can be mentioned. In many applications a large surface area is desired. Surface enhancements can be done in several ways; one way is to deposit the desired material on a template with a high surface area. Anodic aluminium oxide (AAO) is a suitable template, since it has a high surface area and it also possesses a high degree of order. The porous structure of the AAO puts high demands on the deposition method, especially when depositing a non-conducting material. One technique that meets these demands is atomic layer deposition (ALD).

In this study thin films and nanotubes of iron oxide have been successfully deposited using atomic layer deposition (ALD) with the precursor combination ferrocene Fe(Cp)2 and oxygen. Thin films and nanotubes have been grown on Si (100) and anodic aluminium oxide (AAO), respectively. Depositions were carried out in the temperature region of 350 °C to 600 °C on Si (100) and at 400 °C on AAO. The growth per cycle values were around 0.14 nm on Si (100) and 0.06 nm on AAO. Quartz crystal micro balance (QCM) showed that the process exhibited ALD characteristics. GIXRD showed that below 500 °C the iron oxide crystallised as a phase mixture consisting of the rhombohedral Fe2O3 phase (hematite) and a second phase that could not be unambiguously identified. Above 500 °C only phase pure hematite was detected. XPS analysis showed a carbon contamination level of around 1-3 at-%. For deposition of nanotubes both commercial and in-house made AAO membranes were used, having aspect ratios of 200 and 35, respectively. By etching of the in-house made AAO membranes after deposition, free-standing nanotubes retaining the order of the AAO template could be fabricated. The nanotubes were supported by either silver rods or glue.

 

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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium C, by Mårten Rooth
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-21 16:27
Revised:   2009-06-07 00:44