Abstract
Optical and electrical properties of sputter-deposited FeSi(2) thin films on p-Si(100) and SiO(2)/p-Si(100) substrates as well as their evolution with rapid thermal annealing (RTA) temperature have been investigated. Optical absorption measurements were carried out to determine the absorption spectra of FeSi(2) based on the proposed optical absorption model for the double-layer and triple-layer structures. A direct band gap behavior was concluded for both amorphous and polycrystalline semiconducting FeSi(2). An absorption coefficient in the order of 105 cm(-1) at 1 eV and a band gap value of similar to 0.86 eV were obtained for the beta-FeSi(2). Hall effect measurements at room temperature indicate heavily doped and n-type conductivity for the FeSi(2) films on p-Si, whose residual carrier concentration was found to be closely correlated with the observed subgap optical absorption via band tailing. The carrier mobility was shown to increase with decreasing residual carrier concentration when the RTA temperature was increased. 0 2008 American Institute Of Physics. [DOI: 10.1063/1.2981198]