| In the 21st century, the speed of information processing has a rapid development, but it tends to a limit. As all is known, silicon plays an important part in microelectronic filed, and it is a basic material on integrated circuit. However, single crystal silicon for the band gap 1.12eV, is an indirect band gap semiconductor, and electron can't transit from the bottom of conduction band to the top of valence band directly. Moreover, the wavelength of silicon is 1.141μm and has only an inefficient infrad light. So there are some limits for silicon material applied in photoelectric filed. However, due to extensive resources, low cost, high purity of silicon and fine silicon planar technology, people haven't given up the realization of silicon-based optoelectronic integrated efforts. So far, these researches include silica-base super crystal luminescent material, silica-base heteroepitaxy luminescent material, silicon and carbon alloy and porous silicon (PS) and so on.In this paper, PS sample was prepared by double-tank electrochemical corrosion method, and morphologies of PS samples were observed by means of Atomic Force Microscopy (AFM) SPA-400 and Scanning Electronic Microscope (SEM). PS morphologies, porosity and layer thickness which is effected by etchng time is analyzed, which is a base for PS formation mechanics. From this paper, it is found that PS porosity is respective 48%,50%,60%,67%,55.6%and 54%, and the PS porosity is maxium when the etching time is 40min. Meanwhile, the tendency between layer thickness and etching time is found from the expenmental datas (1.25μm,1.3μm, 1.5μm,1.6μm,1.58μm,1.4μm). Layer thickness is increasing at first, and then is lower with the etching time increasing, so is photoluminescence (PL) intensity. The PL intensity first increases from 26.18 to 72.09, and then decreases to 16.3. Meanwhile, the trend of porosity and PL spectrum with changing etching time confirm that it is necessary for improving PL intensity to increase porosity.In order to improve PL intensity and stability of PS, the researchers have studied various metal depositions on PS surface, and the research shows that there is an important significance on improvemt of PS structure and its PL performance. Among various metal species, copper has been extensively studied because it is a common contaminant with a tendency to deposit easily from aqueous fluoride solutions. Moreover, copper is expected to replace aluminum as the metallization of choice in microelectronic. In this paper, the solid-liquid interface reaction and deposit copper on the surface of porous silicon (PS) are used. From AFM morphology images of PS samples about pre-deposition and post-deposition, it is found that there are mainly two kinds of morphologies on the surface of post-deposition PS, one is tube, and the other one is non-tube film. In the photoluminescence (PL) spectrums of porous silicon with per-deposition and post-deposition, it was clearly observed that the PL intensity of PS with the tubular membrane on the surface (etching time 40min, deposition time lmin) is 821.2, which increased by 40% compared with per-deposition, and the PL intensity did not decrease 4 months later. While the PL intensity of PS with the non-tubular membrane (etching time 60min, deposition time lmin) is 224.7, which increased by 20% compared with per-deposition. X-ray Photoelectron Spectroscopy (XPS) and Fourier Infrared Spectroscopy (FTIR) analysis were carried out to come to the conclusion:(1) The thin copper film are as impurities and defects in SiO2 on the surface of PS. (2) All the impurities, defects and surface resonance excitation on the copper film can enhance PL intensity. (3) The copper film suppresses the natural oxide of the silicon nanowires and has a stabilizing effect to Si-H bonds, which enhances the stability of the emission spectra. |
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