| Silicon (Si)-based electronics and integrated circuits have become a pillar in the high-tech fields of computer, communications, electronic control and information processing development in contemporary. Therefore, silicon-based semiconductor electronics industry has become the leading of information industry. High-efficiency light-emitting silicon-based material can determine the leading role of silicon-based material in the optoelectronic position. However, Si is an indirect band gap material, the conduction band and valence band of the lowest K value is not at the same point of the space. According to the principle of conservation K, the composite of electrons injected into the Si conduction band and holes in the top of the Si valence band have to rely on the participation of phonon, which is a many-body transition process, with the efficiency of inter-band recombination luminescence at least three orders of magnitude smaller than GaAs. So looking for new high-efficiency silicon light-emitting materials and devices has been the focus attention of scientists and engineers.The key of high efficiency light-emitting silicon compound materials, compatible with silicon technology is that the material band gap energy is smaller than Si (1.1eV) and the lattice constant should be close to Si, so it can matching with the growth of Si.β-FeSi2 is a promising and attractive material for being used in silicon-based optoelectronics due to its excellent electronic and optical properties. For its optical direct band gap is about 0.80-0.89 eV, corresponding to a wavelength of 1.5μm luminescence, which is close to the minimum absorption windows of the silica-based optical fibers. The semiconductingβ-FeSi2 has been intensively studied for light emission devices, high-efficiency material in solar energy conversion cells, and photo-detectors for its high photoelectric conversion efficiency of 16-23﹪. Besides, β-FeSi2 is considered to be ecologically-friendly material for its component elements are nontoxic and abundant in the earth's crust.As it was reported that the properties of theβ-FeSi2 films are depend on the surface conditions of the films and the deposition methods. It is very important to find out the appropriate method and the experimental conditions for the preparation of theβ-FeSi2 films with good surface morphologies. In this paper, we have prepared theβ-FeSi2 films by pulsed laser deposition and thermal annealing; we investigated the structural properties and crystallographic orientation of the films by X-ray diffraction (XRD) analysis. The scanning electron microscopy (SEM) and Atomic force microscope (AFM) were used to determine the structural properties and surface images of the films. The Fourier transform infrared (FTIR) spectroscopy was also used to characterize the fabricatedβ-FeSi2 films. The main results obtained are as follows:First, we have prepared the single phaseβ-FeSi2 films by the process of pulsed laser deposition and thermal annealing. And we investigated the films by X-ray diffraction (XRD) analysis, the scanning electron microscopy (SEM), Atomic force microscope (AFM) and the Fourier transform infrared (FTIR) spectroscopy.Second, after comparing the results, we conclude that the crystallization degree, size and shape of the grains and the surface roughness are all changed regularly with increases of sputtering time. We finally found the most appropriate sputtering time of 40 min under the experimental conditions.Third, we changed the distance between target and substrate (Dt-s) to obtain the preferentiallyβ-FeSi2 thin films, and we finally found the film fabricated at the distance of 40 mm is the best. The roughness is the minimum and the particle distribution of the film surface is more uniform, the infrared absorption degree is the highest. Forth,we analyzed the effect of different substrates and annealing environment to the structural properties of the preparedβ-FeSi2 films by XRD, SEM results.We found that, films grown on Si(100) have better surface morphology, while the thin films grown on Si(111) have high quality. After high temperature annealed, theβ-FeSi2 films oriented well than films annealed in situ.Fifth,we studied the surface morphology and polycrystalline structure of theβ-FeSi2 films, we also analized the growth mechanism of theβ-FeSi2 films briefly.
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