The in-plane orientations of Si/SiC heterojunctions on 6H-SiC(0001) were investigated by high-resolution X-ray diffraction. An SiIJ111)/SiC(0001) heterostructure with an in-plane orientation of Siij01−1]//SiC[110] is achieved at 900 °C, the Si/6H-SiC interface has a 4 : 5 Si-to-SiC matching mode with a residual lattice mismatch of 0.26%, and the edge dislocation density at the Si/SiC interface is calculated to be 4.87 × 10 13 cm −2 . As the growth temperature is increased to 1050 °C, the [110] preferential growth with an in-plane orientation of Siij−110]//SiC[0−10] is observed, along Siij001]SiC [210] orientations, the Si-to-SiC mode changes to approximately 1 : 2 and the residual mismatch is 1.84%. The edge dislocation density increases to 1.22 × 10 14 cm −2 correspondingly.
The Si/SiC heterojunctions were prepared on 6H-SiC (0001) C-face by low-pressure chemical vapour deposition at 850 ∼ 1050 °C. Transmission electron microscopy and selected area electron diffraction were employed to investigate the interface-structure of Si/SiC heterojunctions. The Si/6H-SiC heterostructure of large lattice-mismatch follows domain matching epitaxy mode, which releases most of the lattice-mismatch strain, and the coherent Si epilayers can be grown on 6H-SiC. Si(1-11)/6H-SiC(0001) heterostructure is obtained at 900 °C, and the in-plane orientation relationship of Si/6H-SiC heterostructure is (1–11)[1-1-2]Si//(0001)[-2110]6H-SiC. The Si(1-11)/6H-SiC(0001) interface has the same 4:5 Si-to-SiC matching mode with a residual lattice-mismatch of 0.26% along both the Si[1-1-2] and Si[110] orientations. When the growth temperature increases up to 1000 °C, the ⟨220⟩ preferential orientation of the Si film appears. SAED patterns at the Si/6H-SiC interface show that the in-plane orientation relationship is (-220)[001]Si//(0001)[2-1-10]6H-SiC. Along Si[110] orientation, the Si-to-SiC matching mode is still 4:5; along the vertical orientation Si[001], the Si-to-SiC mode change to approximate 1:2 and the residual mismatch is 1.84% correspondingly. The number of the atoms in one matching-period decreases with increasing residual lattice-mismatch in domain matching epitaxy and vice versa. The Si film grows epitaxially but with misfit dislocations at the interface between the Si film and the 6H-SiC substrate. And the misfit dislocation density of the Si(1-11)/6H-SiC(0001) and Si(-220)/6H-SiC(0001) obtained by experimental observations is as low as 0.487 × 1014 cm−2 and 1.217 × 1014 cm−2, respectively, which is much smaller than the theoretical calculation results.
Micropipe is a vital defect for fabricating SiC based devices. In order to understand the evolution of micropipe during growth process, the authors studied axial cuts sliced from different parts of the sublimation grown SiC single crystals. The cuts have been characterised using optical microscopy, etching in molten mixed KOH and K 2 CO 3 , scanning electron microscope and X-ray photoelectron spectroscopy. It is found that second phase inclusion (silicon droplet) is contributing not only to the formation of micropipe defect but also to its termination during SiC growth process. And X-ray photoelectron spectroscopy measurement result shows that growth interface can be demarcated obviously without intentionally doping any other impurity, which offers a good and simple method for observing crystal growth process.
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