Ion beam induced solid state reaction in Si/C layer systems

Ion irradiation (350 keV Xe ions) of Si/C layer systems leads to atomic mix ing and a solid state reaction between the two constituents. The ballistic model underestimates the ion beam mixing rate and, in contradiction to the model, a quadratic dependence between the applied fluence and the thickness of the intermixed layer was found. This is a hint that chemical driving fo rces have to be taken into account. For the evolution of the chemical short range order in the intermixed material two temperature regions can be dist inguished. If the irradiation is carried out below 873 K an amorphous netwo rk forms which exhibits no uniform short range order. At higher temperature s (similar to 873 K) a well-defined short range order forms which compares to that of crystalline SiC. Annealing experiments indicate that the phase f ormation is not a simple temperature effect, but the energy deposition by t he ion beam is necessary for the formation of the SIC short range order. (C ) 2001 Elsevier Science B.V. All rights reserved.