Reduction of the C49→C54 phase transformation temperature in co-sputtered TiSi2 thin films by ternary alloying

The phase transformation behavior in binary and some ternary TiSi2 thin films produced by co-sputtering has been investigated as a function of annealing temperature, in an attempt to reduce the C49-->C54 phase transformation temperature by increasing the relative stability of the C54 modification with respect to the C49 modification through ternary alloying. Ternary elements investigated include Nb, Mo and Au, all of which have an electronegativity greater than that of Ti and thus are expected to increase the relative stability of the C54 modification by increasing the covalency of the C54 modification. The C49-->C54 phase transformation temperature is indeed found to decrease by 50 degreesC for Nb- and Mo-bearing thin films and by 100 degreesC for Au-bearing thin films when compared to that for binary thin films. The reduction in the phase transformation temperature by ternary alloying is in increasing order of the electronegativity of the ternary elements investigated. Thus, the electronegativity of ternary elements is found to be a good guide for controlling the relative stability of the C54 modification with respect to the C49 modification and therefore for controlling the C49-->C54 phase transformation temperature. (C) 2003 Elsevier Science Ltd. All rights reserved.