beta-FeSi2 films were prepared on Si(001) substrates by the molecular beam epitaxy method using an Fe source. The crystallographic orientation of beta-FeSi2 films on Si(001) substrates were characterized by using x-ray diffraction. Using scanning electron microscopy, surface morphology and film thickness of an oriented sample were observed and estimated. The mobility of beta-FeS2 films on Si(001) substrates was also characterized by Hall measurement at room temperature. The enhancement of figure of merit was evaluated as the functions of mobility and crystallographic orientation of samples.