Formation of β-SiC on por-Si/mono-Si surface according to stranski - krastanow mechanism

Abstract

We report the synthesis of β-SiC/por-Si/mono-Si heterostructure by a hybrid method, consisting of the electrochemical etching of the single-crystal silicon surface with a subsequent carbidization by a thermal annealing in a methane atmosphere. This method has a number of advantages over the known ones, because it is cheap enough and allows one to form the silicon carbide layers of high- quality. The formed structure was studied by means of SEM, EDX and XRD methods. As a result, the dense β-SiC layer, consisting of an array of the spherical islands with diameters of 2–6 μm, coated with the small pores, was formed on the por-Si/mono-Si surface. The geometric dimensions of the islands were studied by calibrating the sample image in the ImageJ software package. The maximum value of the linear size (diameter) of the island dmax = 5.95 μm and the minimum value dmin = 2.11 μm were found in the studied area. In general, the average diameter of the islands is d = 3.72 μm. The distribution has the left-sided asymmetry, that is, the smaller islets predominate. Roundness (the ratio of the area to the square of the larger axis) R = 0.86. According to the results of EDX analysis, it was found that the synthesized structure surface consists exclusively of the carbon and silicon atoms, indicating the high quality of the formed structures. It was found that the SiC film crystallizes in the cubic phase. The formation of the islands is explained by means of the layer-plus-island growth model according to Stranski-Krastanow mechanism, which is characterized by the formation of the dense wetting layer with the massive island complex on the surface. It should be also noted that the porous SiC layers of island type can, in turn, show the perspective as the buffers with the heteroepitaxy of the silicon substrate materials.