Nanocrystalline SiC films prepared by direct deposition of carbon and silicon ions

The method of direct deposition of carbon and silicon ions was used for preparation of nanocrystalline silicon carbide films. The deposition energy of carbon and silicon ions was 90 eV The effect of substrate temperature in the range of 500-1150 degrees C on the structure of SiC films was studied by means of X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). According to XPS data, the films contained heterobonded Si-C atoms and homobonded Si-Si and C-C atoms, the relation between which varied as the function of substrate temperature. The data of XRD showed a noticeable growth of a nanocrystalline phase of cubic silicon carbide in the films at a temperature of about 700 degrees C. The content of 3C-SiC nanocrystalline phase reached 80 at.% at 950 degrees C. There was an established change from cubic polytype to rhombohedral polytype of silicon carbide alpha-SiC-21 R at a substrate temperature higher than 1000 degrees C. The size of SiC crystal grains depended on the substrate temperature and changed from 4-5 up to 8-10 nm over the range of 700-950 degrees C. Besides, silicon unbonded with carbon also crystallized in nanocrystalline form with similar sizes of crystal grains. A possible model of the change of the polytypic composition of SiC film under the conditions of direct ion deposition was discussed. (C) 2007 Elsevier B.V. All rights reserved.