Structural and optical properties of beta -FeSi_2/Si(100) prepared by laser ablation method

摘要

beta -FeSi_2 is a promising material for the application of varous electronic, optoelectronic and energy devices. We present here the semiconducting properties of beta -FeSi_2 films on Si(100) substrate prepared by laser ablation method. Samples were grown using poly-crystalline bulk beta -FeSi_2 prepared by horizontal gradient freeze method. For the monitoring of growth, in-situ observation of ablation plume was made through fluorescence spectroscopy. Reflection of high-energy electron beam diffraction (RHEED) was also made in-situ to see the surface morphology. Characterization of the films by X-ray diffraction presented purely beta (220) orientation. Raman scattering measurements at room temperature also indicated that the grown films are semiconducting beta -Fe-Si_2. Optical absorption spectra at room temperature showed absorption ocefficient higher than 10~5 cm~(-1) above the band-gap (approx 1.2 eV). It was revealed that high quality semiconducting beta -FeSi_2 films can be fabricated by laser ablation method without post-annealing.