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Ultrathin ZrO2 films on Si-rich SiC(0 0 0 1)-(3 × 3): Growth and thermal stability
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
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2007 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 11, 2390-2400 p.Article in journal (Refereed) Published
Abstract [en]

The growth and thermal stability of ultrathin ZrO2 films on the Si-rich Si(0001)-(3 x 3) surface have been explored using photoelectron spectroscopy (PES) and X-ray absorption spectroscopy (XAS). The films were grown in situ by chemical vapor deposition using the zirconium tetra tert-butoxide (ZTB) precursor. The O 1s XAS results show that growth at 400 degrees C yields tetragonal ZrO2. An interface is formed between the ZrO2 film and the SiC substrate. The interface contains Si in several chemically different states. This gives evidence for an interface that is much more complex than that formed upon oxidation with O-2. Si in a 4+ oxidation state is detected in the near surface region. This shows that intermixing of SiO2 and ZrO2 occurs, possibly under the formation of silicate. The alignment of the ZrO2 and SiC band edges is discussed based on core level and valence PES spectra. Subsequent annealing of a deposited film was performed in order to study the thermal stability of the system. Annealing to 800 degrees C does not lead to decomposition of the tetragonal ZrO2 (t-ZrO2) but changes are observed within the interface region. After annealing to 1000 degrees C a laterally heterogeneous layer has formed. The decomposition of the film leads to regions with t-ZrO2 remnants, metallic Zr silicide and Si aggregates.

Place, publisher, year, edition, pages
2007. Vol. 601, no 11, 2390-2400 p.
Keyword [en]
zirconium dioxide; silicon carbide; chemical vapor deposition; semiconductor-insulator interfaces; synchrotron radiation photoelectron; spectroscopy; X-ray absorption spectroscopy
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-94711DOI: 10.1016/j.susc.2007.04.026ISI: 000247408600016OAI: oai:DiVA.org:uu-94711DiVA: diva2:168667
Available from: 2006-09-04 Created: 2006-09-04 Last updated: 2012-10-09Bibliographically approved
In thesis
1. Surface Science Studies of Metal Oxides Formed by Chemical Vapour Deposition on Silicon
Open this publication in new window or tab >>Surface Science Studies of Metal Oxides Formed by Chemical Vapour Deposition on Silicon
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For an electronic device well-designed interfaces are critical for the performance. Studies of interfaces down to an atomic level are thus highly motivated both from a fundamental and technological point of view. In this thesis, a surface science approach has been employed to study the formation of interfaces in systems relevant for transistor and solar cell applications. Surface science methodology entails ultra high vacuum environment, single crystalline surfaces, submonolayer control of deposited material, surface sensitive spectroscopy and atomic resolution microscopy.

The primary experimental method for characterization is electron spectroscopy. This is a family of very powerful experimental techniques capable of giving information on the atomic level. Additionally, studies have been performed using scanning tunnelling microscopy. Combined these two methods can provide an atomic level characterisation of the geometric and electronic properties of the surface.

The emphasis of this work is placed on ultra thin TiO2 and ZrO2 films grown on silicon substrates by means of ultra-high vacuum metal-organic chemical vapour deposition. ZrO2 has also been grown on SiC and FeCrAl. Deposition has been performed with different process parameters. The interface region of each film has been characterised. The band alignment, a most important issue with regard to the development of new transistor devices, for the ZrO2/Si(100) system has been explored. Decomposition pathways of the metal organic precursors have been studied in detail. Changing process parameters is shown to alter both the precursor decomposition pathway and the nature of the interface region, thus opening the possibility to tailor the material function.

The titanium dioxide films grown in situ have shown to be excellent models of nanostructured electrode materials. In this spirit, interfaces of model systems for the solid-state dye-sensitized solar cell have been studied. Links between device performance and interface structure have been elucidated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 58 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 203
Physics, chemical vapour deposition, high-k, metal oxides, silicon, dye-solid interface, metal organic, electron spectroscopy, scanning tunnelling microscopy, Fysik
urn:nbn:se:uu:diva-7088 (URN)91-554-6622-2 (ISBN)
Public defence
2006-09-29, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2006-09-04 Created: 2006-09-04 Last updated: 2012-10-09Bibliographically approved

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