Binary Ta-Si and ternary Ta-Si-N films of various compositions were deposited by reactive r.f. magnetron sputtering from Ta5Si3 target and tested as diffusion barriers between GaAs and Au. All as-deposited films were amorphous and conducting. Their resistivity and crystallisation temperature increased with increasing nitrogen. While nitrogen-free Ta-Si films crystallised at 600degreesC, for the most stable Ta34S25N41 layers crystallisation occurred above 900degreesC. 100 nm thick Ta34S25N41 films prevented interaction between Au and GaAs during annealing at temperatures up to 800degreesC. (C) 2003 Elsevier B.V. All rights reserved.