Growth and doping of silicon carbide with germanium: a review

This paper review the research works made so far in associating Ge isoelectronic element to SiC crystals, either by incorporating it inside SiC matrix or for assisting SiC epitaxial growth. The incorporation mechanism and level of incorporation of Ge in SiC during crystal growth with different techniques (sublimation, chemical vapor deposition, vapor-liquid-solid) are compared and discussed. Ge doping level as high as 2-3x1020 at.cm−3 can be reached without affecting SiC crystalline quality but generating some strain. Higher Ge incorporation levels up to few at% can be reached using farer-to-equilibrium conditions such as ion implantation or molecular beam epitaxy. The former allows retaining 4H-SiC polytype while the latter leads exclusively to defective 3C-SiC polytype. Adding Ge to SiC crystal growth was also used for promoting 3C-SiC heteroepitaxy on Si and on α-SiC substrates, the latter case being more successful. The reported modifications and improvements of SiC crystalline and electronic properties by the incorporation of Ge element are discussed in order to draw or clearer picture of SiC:Ge material. Based on such discussion, some short- and long-term perspectives are proposed