| As a novel of semiconductor material,β-FeSi2 with Orthorhombic structure has a direct band gap of around 0.85-0.87eV according to a wavelength of 1.3-1.5um.In addition,it has an ultrahigh optical absorption coefficient and a theoretical solar energy conversion efficiency of as high as 16%-23%.Moreover,β-FeSi2,a environment-friendly semiconductor,having a structure compatible with silicon technology.Such features ofβ-FeSi2 make it suitable for using in the silicon-based semiconductors and optoelectronic,thermoelectronic,and photovoltaic devices.Besidesβ-FeSi2 is a very promising material for a new solar cell with a high absorption of light.However,there is no conclution in the property of band gap ofβ-FeSi2.The luminescence signal ofβ-FeSi2 is too weak to achieve the required level of application.In the previous study,we have successfully prepared multilayer films withβ-FeSi2 nano-particles/a-Si structure,and measured luminescent properties of multilayer films at RT.During the study,we found the trend of interlayer diffusion inβ-FeSi2 particles after 850℃/8h annealing.Therefore,this experiment attempted to long time annealing in order to study impact of annealing on the stability of multilayer films.Simultaneously,we tried to prepare silicon iron film by other methods.The structure,composition and optical properties of the films were also characterized and analyzed.Paper has the following two parts:â… .Better continuity and formation of the Fe/Si multilayer films was successfully deposited on Si(100) substrate using radio frequency magnetron co-sputtering method.Study the stability of multilayer structure through 850℃/12h annealing.The results found that there is no change in phase composition,but the structure is no longer stable after 12h annealing.It is surprising to form a thick layer of amorphous Si layer after annealing.We think that the amorphous layer resulted from non-crystallization of substrate Si.and with increasing of the deposition time of silicon,the amorphous Si in original multi-layer films have also contributed.The Amorphous layer generate firstly at the the side ofβ-FeSi2 particles.The increasing of amorphous silicon was supplyed from Si substate,and at the same time,the remainingβ-FeSi2 will spread across amorphous silicon layer to iron silicon layer at the the top of sample.The change from crystal silicon to amorphous silicon needs promotion of Fe. amorphous iron silicon in samples significantly contributes to the absorption.â…¡.Iron silicon film was successfully deposited on Si(100) substrate using unbalanced magnetron sputtering.The effect of iron deposition power changes,including hydrogen or not,and annealing to structure and property of films were studied,β-FeSi2 grains embedded in amorphous phase were deposited when Fe power is 40W or 50W.During characterizing band gaps of the annealed and as deposited,it is found that a certain proportion of amorphous iron silicon had also contributed to absorption,which confirmed that a certain proportion of iron silicon has semiconductor property.
|
PDF Full Text Request