Ultrathin ZrO2 films on Si-rich SiC(0 0 0 1)-(3 × 3): Growth and thermal stability
2007 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 11, 2390-2400 p.Article in journal (Refereed) Published
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.
zirconium dioxide; silicon carbide; chemical vapor deposition; semiconductor-insulator interfaces; synchrotron radiation photoelectron; spectroscopy; X-ray absorption spectroscopy
IdentifiersURN: urn:nbn:se:uu:diva-94711DOI: 10.1016/j.susc.2007.04.026ISI: 000247408600016OAI: oai:DiVA.org:uu-94711DiVA: diva2:168667