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Engineering Epitaxial Gamma-Al-2O-3 Gate Dielectric Films on 4H-SiC

The formation of epitaxial {gamma}-Al{sub 2}O{sub 3} thin films on 4H-SiC was found to be strongly dependent on the film thickness. An abrupt interface was observed in films up to 200 {angstrom} thick with an epitaxial relationship of {gamma}-Al{sub 2}O{sub 3}(111) {parallel} 4H-SiC(0001) and {gamma...

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Bibliographic Details
Published in:Journal of applied physics 2009-04, Vol.102 (10)
Main Authors: Tanner, C.M., /UCLA, Toney, M.F., /SLAC, SSRL, Lu, J., Blom, H.O., /Uppsala U., Sawkar-Mathur, M., Tafesse, M.A., Chang, J.P.
Format: Article
Language:English
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Summary:The formation of epitaxial {gamma}-Al{sub 2}O{sub 3} thin films on 4H-SiC was found to be strongly dependent on the film thickness. An abrupt interface was observed in films up to 200 {angstrom} thick with an epitaxial relationship of {gamma}-Al{sub 2}O{sub 3}(111) {parallel} 4H-SiC(0001) and {gamma}-Al{sub 2}O{sub 3}(4{bar 4}0) {parallel} 4H-SiC(11{bar 2}0). The in-plane alignment between the film and the substrate is nearly complete for {gamma}-Al{sub 2}O{sub 3} films up to 115 {angstrom} thick, but quickly diminishes in thicker films. The films are found to be slightly strained laterally in tension; the strain increases with thickness and then decreases in films thicker than 200 {angstrom}, indicating strain relaxation which is accompanied by increased misorientation. By controlling the structure of ultrathin Al{sub 2}O{sub 3} films, metal-oxide-semiconductor capacitors with Al{sub 2}O{sub 3} gate dielectrics on 4H-SiC were found to have a very low leakage current density, suggesting suitability of Al{sub 2}O{sub 3} for SiC device integration.
ISSN:0021-8979
1089-7550