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Gas sensing properties of epitaxial SnO2 thin films prepared by atomic layer deposition
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
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2003 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, Vol. 93, no 1-3, 552-555 p.Article in journal (Refereed) Published
Abstract [en]

Undoped SnO2 thin films are grown on α-Al2O3(0 1 2) (r-cut sapphire) substrates by gas phase atomic layer deposition (ALD). Two precursor pairs, SnI4–O2 and SnCl4–H2O2, both new for ALD, are used. The films have a cassiterite structure and are (1 0 1)[0 1 0]cassiterite||(0 1 2)[1 0 0]sapphire oriented. A good epitaxial quality and the conductivity acceptable from the standpoint of semiconductor gas sensors are achieved for ultrathin films grown from SnI4–O2 at 600 °C. The sensitivity of these films to CO in air has a maximum at a thickness of about 10 nm. Response rise and decay times belonging to a several seconds interval are measured. The films are assumed to function as a single grain.

Place, publisher, year, edition, pages
2003. Vol. 93, no 1-3, 552-555 p.
National Category
Inorganic Chemistry
URN: urn:nbn:se:uu:diva-90496DOI: 10.1016/S0925-4005(03)00236-3OAI: oai:DiVA.org:uu-90496DiVA: diva2:162867
Available from: 2003-05-13 Created: 2003-05-13 Last updated: 2013-09-06Bibliographically approved
In thesis
1. Employing Metal Iodides and Oxygen in ALD and CVD of Functional Metal Oxides
Open this publication in new window or tab >>Employing Metal Iodides and Oxygen in ALD and CVD of Functional Metal Oxides
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Many materials exhibit interesting and novel properties when prepared as thin films. Thin film metal oxides have had an impact on the technological progress of the microelectronics mainly due to their electrical and optical properties. Since the future goes towards the nanometre scale there is an increasing demand for thin film deposition processes that can produce high quality metal oxide films in this scale with high accuracy.

This thesis describes atomic layer deposition of Ta2O5, HfO2 and SnO2 thin films and chemical vapour deposition of SnO2 thin films. The films have been deposited by employing metal iodides and oxygen as precursors. All these processes have been characterised with regards to important processing parameters. The films themselves have been characterised by standard thin film analysing techniques such as x-ray diffraction, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. The chemical and physical properties have been coupled to critical deposition parameters. Furthermore, additional data in the form of electrical and gas sensing properties important to future applications in the field of microelectronics have been examined.

The results from the investigated processes have shown the power of the metal iodide based atomic layer deposition (ALD) and chemical vapour deposition (CVD) processes in producing high quality metal oxide thin films. Generally no precursor contaminations have been observed. In contrast to metal chloride based processes the metal iodide processes produces films with a higher degree of crystalline quality when it comes to phase purity, roughness and epitaxy. The use of oxygen as oxidising precursor allowed depositions at higher temperatures than normally employed in water based ALD processes and hence a higher growth rate for epitaxial growth was possible.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 66 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 852
Inorganic chemistry, CVD, ALD, tantalum oxide, hafnium oxide, tin oxide, epitaxy, Ta2O5, HfO2, SnO2, XRD, Oorganisk kemi
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
urn:nbn:se:uu:diva-3450 (URN)91-554-5660-X (ISBN)
Public defence
2003-06-03, Polhemsalen, The Ångström Laboratory, Uppsala University, Uppsala, 13:15
Available from: 2003-05-13 Created: 2003-05-13 Last updated: 2013-06-13Bibliographically approved

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Aidla, Alex
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