3. Conclusions

In this chapter, Si/SiC heterostructures with different orientations were prepared on 6H-SiC(0001) by LPCVD. The heterostructure of large lattice-mismatch grows by DM mode, which releases most of the lattice-mismatch strain, and the coherent Si epilayers can be grown on 6H-SiC. Si(111)/6H-SiC(0001) heterostructure obtained at 900C has an in-plane orientation relationship of (111)[1-10]Si//(0001)[1-210]6H-SiC. The Si(111)/6H-SiC(0001) interface has the 4:5 Si-to-SiC matching mode with a residual lattice-mismatch of 0.26% along both the Si[11-2] and Si[1-10] orientations. As the growth temperature increases to 1050C, the preferential orientation of the Si film transitions to [110]. SAED patterns show that the in-plane orientation relationship is (110)[001]Si//(0001)[10-10]6H-SiC. Along Si[-110] orientation, the Si-to-SiC matching is still 4:5; along the vertical orientation Si[001], the matching mode is approximate 1:2 and the residual mismatch is 1.84% correspondingly. The atom quantity in one DM period decreases with increasing residual mismatch and vice versa. The Si film epitaxially grows but with MDs at the Si/6H-SiC interface. The MD density of the Si(111)/6H-SiC(0001) and Si(110)/ 6H-SiC(0001) obtained by experimental observations is as low as 0.487 and 1.217 <sup>10</sup><sup>14</sup> cm<sup>2</sup> , respectively, which is much smaller than the theoretical value.
