Investigation of physical properties and synthesis of ß-FeSi2 thin films

ß-FeSi2 thin films were grown on n-Si (100) and p-Si (111) substrates at room temperature by unbalanced magnetron sputtering and ß-FeSi2/n-Si and ß-FeSi2/n-Si heterojunctions were thus prepared. The originality of the study is the achievement of heterojunctions without any further heat treatment of the deposition films. Pure iron is deposited on Si substrates with unbalanced magnetron sputtering for the production of ß-FeSi2/Si heterojunctions with different film thicknesses. Prior to coating process the target and substrates are cleaned with neutral molecular source.Microstructure of ß-FeSi2 films were investigated by X-Ray Diffraction analysis and Raman spectroscopy. Elemental analyses of ß-FeSi2 films were made using Energy Dispersive Spectroscopy and Glow Discharge Optical Emission Spectroscopy. Surface properties of ß-FeSi2 films were characterized with Scanning Electron Microscopy, Field Emission Scanning Electron Microscopy and Atomic Force Microscopy. The ß-FeSi2 films were found to be polycrystalline in nature. Surface morphology and crystallinity of the template layers were found to depend on the surface conditions of substrates. ß-FeSi2 films with very smooth surfaces can be obtained by optimization of substrate surface properties and coating parameters.Optical absorption coefficients of the ß-FeSi2 films at room temperature were evaluated from the Fourier Transform Infrared Spectroscopy measurements. The optical absorption in the edge region of these ß-FeSi2 films was evaluated as Eg=0,85 eV which is characteristic for a direct transition semiconductor. The electrical properties obtained from current-voltage characteristics (I-V) of ß-FeSi2/n-Si and ß-FeSi2/n-Si heterojunctions at room temperature have been investigated. Dark current-voltage characteristics of the deposited coatings showed a rectifying behaviour for the heterojunctions.The diode parameters such as zero-bias barrier height and ideality factor were determined using thermionic emission theory.However, we have investigated the effect of ion bombardment during and after deposition on the structure and surface properties of semiconducting ß-FeSi2 thin films grown on n-Si (100) substrates at room temperature by unbalanced magnetron sputtering.