Thermodynamic investigations of solid-state Si-metal interactions. I, experimental and analytical studies of the Si-Ti binary system

An experimental study has been made on reactions in codeposited and multilayer films consisting of silicon and titanium deposited by electron beam evaporation. Transmission electron microscopy and Auger electron spectroscopy were used to determine structures and compositions. The experimental results from the codeposited films in the whole composition range (0%–100%) were compared with the predictions from the calculated free-energy diagram of the Si-Ti system. It is revealed that the phenomena of metal-induced crystallization of amorphous silicon and formation of amorphous alloys appear in two different composition ranges in the binary system. Metal-induced crystallization of amorphous silicon is attributed to lowering of bonding energy of SiSi bonds by titanium atoms in the Si-rich composition range and the formation of an amorphous Si-Ti alloy is attributed to the dominant SiTi bonding due to the largely negative heat of mixing between the two elements in a medium composition range.