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Growth and Characterisation of Heavily Al-Doped 4H-SiC Layers Grown by VLS in an Al-Si Melt

We report on a new approach in which the homoepitaxial growth of 4H-SiC layers can be done at low temperature (1100°C). The process involves a VLS (Vapor-Liquid-Solid) mechanism in which propane feeds an Al-Si droplet. Compared to conventional LPE (Liquid Phase Epitaxy) this approach has several advantages. No thermal gradient (vertical or radial) has to be controlled and the liquid can be easily removed before cooling by sucking up the melt. In this way, Al concentrations in the range ~ 1-3.10 20 at.cm -3 have been reached and, both, Raman and TEM characterizations show that no foreign polytype or other material inclusion is formed. The main drawback is a large step bunching, typical of LPE samples.