Synthesis Of High Density Silicon Nanowires By Solid-liquid-solid Method And Their Optical Properties

Use Au/Al alloy as metal catalyst, based on solid-liquid-solid(SLS) growth mechanism, large area of Si nanowires(Si NWs) with the density of 1010/cm2 were directly grown from the single crystal Si(100) substrates. The diameter of Si NWs is about 100 nm and several microns to tens of microns in length. The effects of metal film component and thickness, the substrate morphology, growth time on the formation of the Si NWs. The photoluminescence properties and reflective characteristics of Si NWs were investigated. The microstructure and morphology, chemical compositions, growth crystall orientation, PL characteristics and reflectivity of the Si NWs were characterized and analyzed by scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy(EDS), X-ray powder diffraction(XRD), F4600 fluorescence spectrometer and D8 reflectivity measuring instrument. The results indicated that when the temperature is 1100℃, the flow of N2 is 1.5L/min, using Al/Au alloy as metal catalyst can synthesis high density Si nanowires with similar direction and uniformed distribution. And the density of Si NWs use Au/Al as the catalyst reached 1010/cm2, which are two orders of magnitude larger than the Si NWs use Au as the catalyst. The room temperature photoluminescence(PL) properties of the Si NWs were observed by Xe lamp. The results shown that the Si NWs have a strong ultraviolet emission peak at 355~390nm, and a weak blue emission peak at 458~475nm, the peaks are located at 369 nm and 467 nm respectively, and related to the defect luminescence center from Si Ox. In 350~1000nm wavelength range, The reflectivity of Si nanowires 35% lower than the polished Si substrate.