Studies of oxidized hexagonal SiC surfaces and the SiC/SiO2 interface using photoemission and synchrotron radiation

• Published in: Journal of physics. Condensed matter 2004-05, Vol.16 (17), p.S1783-S1814
• Main Authors: Virojanadara, C, Johansson, L I
• Format: Article
• Language: English
• Subjects: NATURAL SCIENCES; NATURVETENSKAP
• ISSN: 0953-8984; 1361-648X; 1361-648X
• DOI: 10.1088/0953-8984/16/17/017

Results of recent photoemission studies of oxidation of hexagonal SiC surfaces and SiO2/SiC interfaces are reviewed and discussed. These investigations have focused on two main questions thought to have a significant effect on MOS device characteristics: the existence of carbon clusters or carbon containing by-products and the existence of sub-oxides at the SiO2/SiC interface. The presentation is focused on Si-terminated surfaces of hexagonal n-type SiC(0001) crystals since they to date have been considered the most promising for device applications. The results reviewed show that no carbon clusters or carbon-containing by-product can be detected at the interface of in situ or ex situ grown samples with an oxide layer thickness larger than about 10 A. Since the presence of carbon clusters was suggested in a recent scanning microscopy study it appears that they may exist, possibly depending on the sample preparation method used, but in such low concentrations that they are not detectable using photoemission. The presence of sub-oxides at the SiO2/SiC interface has been revealed in recorded Si 2p core level spectra by several groups. The results were not unanimous, however. The number of sub-oxides present and the shifts reported were different. The results of a recent study including also the Si1s core level and Si KLL Auger transitions are therefore examined. These together with earlier Si 2p data show the presence of only one sub-oxide, assigned to Sit' oxidation states, besides the fully developed SiO2 (Si4+).