New Approaches to In Situ Doping of SiC Epitaxial Layers

In this paper, the issues related to in-situ doping of silicon carbide (SiC) semiconductor during epitaxial growth are reviewed. Some of these issues can find solution by using an original approach called vapour-liquid-solid (VLS) mechanism. In this technique, the SiC seed is covered by a Sibased melt and is fed by propane in order to growth the epitaxial film. Using Al-Si melts and temperatures as low as 1100°C, very high p type doping was demonstrated, with a record value of 1.1021 at.cm-3. It leads to very low contact resistivity and even to metallic behaviour of the SiC deposit even at low temperature. Using Ge-Si melts, non intentionally low doped n type layers are grown. By forming Si-containing liquid droplets on a SiC seed, one can extrapolate this VLS growth to selective epitaxial growth (SEG). Such approach was successfully applied for both Al and Ge-based systems in order to form p+ and n doped areas respectively.