Growth by a vapour-liquid-solid mechanism: a new approach for silicon carbide epitaxy

Growing silicon carbide monocrystalline layers at low temperatures (<1400 degrees C) is a challenging problem that requires the development of less conventional epitaxial techniques. Growth from Al-based melts is an interesting alternative that can lead to a more than 300 degrees C temperature reduction compared to that used in the more classical chemical vapour deposition technique. Liquid phase epitaxy under a thermal gradient is often used but this approach has some drawbacks such as the difficulty in controlling the thermal gradient or the presence of the liquid on the seed at the end of the growth. A solution could come from a vapour-liquid solid (VLS) mechanism in which a Si-based melt is fed by an alkane to form SiC on an immersed seed. The growth is then easily controlled by the alkane flux and the liquid can be eliminated in situ by simply sucking it up. We present in this paper a review on the use of the VLS mechanism for growing SiC at low temperatures. Results of the effect of several metal additives (Al, Ni, Fe and Co) to the melt are shown. These metals incorporate into the lattice and can give specific properties to SiC, such as heavily p-type doping with Al or semi-magnetic properties with Ni, Fe or Co. The VLS technique is shown to be very versatile as it can be applied to selective epitaxial growth of SiC. Finally, perspectives of the VLS technique for solving related problems touching SiC or for growing other semiconductor compounds are given.