Characterization of semiconducting silicide films by infrared vibrational spectroscopy

Semiconducting silicides of Fe, Ir, and Mn were grown as thin films mostly on single crystal Si substrates using solid state phase reaction, sputtering and laser ablation of composite targets, coevaporation and MBE. Their phonon spectra were studied by FTIR transmittance measurements between 150 and 550 cm(-1). For each of the investigated silicides a typical IR band pattern has been found. It can be used for phase identification as well as for characterizing the film quality. For microcrystalline beta-FeSi2 a five-line pattern was found. The IR spectra of Ir and Mn silicides are much more complex. Results on beta-FeSi2 show that at a higher degree of crystallinity the spectra become increasingly more structured.