Structural studies of thin silicon layers repeatedly implanted by carbon ions

The composition and structure of homogeneous SiC1.4 and SiC0.12 layers produced by multiple implantation of 40-, 20-, 10-, 5-, and 3-keV carbon ions into silicon were studied by electron microscopy, x-ray diffraction, Auger spectroscopy, and IR spectroscopy. The temperature dependences of the IR transmittance peak parameters obtained in the range 200–1400°C indicate that the increase in the number of carbon atoms that are bound to silicon atoms and are involved in absorption is caused by the formation and breaking of hexagonal, near-tetrahedral, and multiple Si-C bonds and by the decomposition of optically active strong carbon clusters. The high crystallization temperature of SiC (1200°C) in the SiC1.4 layer is explained by the presence of stable multiple Si-C bonds and strong carbon clusters. Strong carbon clusters are shown to exist in the implanted SiC0.12 layer, and their decomposition is found to affect the formation of tetrahedral bonds in the temperature range 1200–1400°C.