Growth and characterization of B-FeSi2 thin films prepared by laser ablation method

Under ultra high vacuum, (beta) -FeSi 2 thin films were formed by laser ablation method using poly crystal (beta) - FeSi 2 as target material that was prepared by horizontal gradient freeze method. In order to compare the physical properties of thin films prepared by laser ablation with those of bulk crystal, (beta) -FeSi 2 single crystal was prepared by chemical vapor transport method. The (beta) -FeSi 2 plate-like and needle-like crystals were formed at 7 mg and 1.0 g of iodine quantity, respectively. To check a crystal symmetry and orientation, Laue transmission patterns were taken. Anisotropic Raman signals were observed from polarized Raman scattering measurements. Further, electron spin resonance measurement was carried out to examine the residual impurities and to determine g values. From (beta) -FeSi 2 films during laser ablation growth, streaky signals were obtained in the RHEED observation. Highly oriented (202)/(220) (beta) -FeSi 2 films were predominantly identified in XRD measurements. Raman scattering and optical absorption measurements for these layers revealed that the grown samples are nearly epitaxially-like and have approximately 0.85 eV as its direct optical band-gap.