Papers by Keyword: Porous Silicon (PS)

Abstract: Detailed studies on Photoluminescence (PL) of porous silicon (PS) with copper deposition were presented. PS was prepared via double electrobath, and then copper was deposited on PS surface by chemical plating. Atomic force microscopy (AFM) measurement indicates that there are different surface morphologies of PS samples with hemispherical, mountain, and tubes-like shape in different etching conditions. PL results show that the PL spectrum intensity of PS with Cu post-deposition increases 50% and do not decay after being laid 4 months than that of PS with pre-deposition. And the peak position from the PL spectrum with Cu deposition has a 14nm blue shift due to the surface stress effect of Cu to PS.

Abstract: A well known method was used to convert the solid silica spheres to porous silicon spheres with high surface area, with the starting shape retained. The presented work demonstrated that the porous silicon spheres are composed of polycrystal morphology. Due to the quantum confinement effect, the photoluminescence emission centered at 621 nm. The results of N2 adsorption and desorption analysis indicates the mesoporous silicon spheres possess a surface area around 88 m2 g-1 and single point micro-pore volume 0.173 cm3 g-1.

Abstract: A novel immunosensor based on porous silicon (PSi) for antigen detection was reported in this paper. The antigen (SpaA) and the specificity of the antibodies are employed as the target and the probe in our laboratory, respectively. The immunosensor structure was prepared using bioconjungation. After the antigen-antibody reaction, the red shift of the reflection spectrum of the immunosensor increases in proportion to the concentration of SpaA. The sensitivity of this immunosensor is 41nm/ µg•ml-1 and the detection limit is 2.44×102pg•ml-1, they are better compared with our previous work by using this method. Controlled experiments were also presented with non-immune antibody and the results show that this immunosensor possesses high specificity.

Abstract: During the chemical synthesis nanometer-sized particles of ferrous iron oxide were in situ infiltrated into the mesopores in a porous silicon film. The microstructures of porous silicon and the magnetic properties of the nanometer-sized particles of the ferrous iron oxide were characterized with scanning electron microscopy, X-ray diffractometry, and the hysteresis loop measurement, respectively. Our results have demonstrated that the magnetic properties of the nanometer-sized Fe3O4 particles can be dramatically modified when they are confined into the mesopores of the porous silicon film.

Abstract: In this article, we report on the observations that in the aqueous electrolyte of aluminum nitrate, the thin metallic conducting films on both internal and external surface of porous silicon (PS) thin films that emit visible photoluminescence at room temperature prior to electrochemical deposition have been obtained under electrochemical deposition condition. Add to this high surface-to-volume ratio and these make it a good candidate for the catalyst supporter. We have investigated the surface morphology of PS after the interval of about 30 hours of electrochemically deposited aluminum by means of scanning electron microscopy (SEM). It has been shown from SEM images that not only micrometer-sized pores are smoothed by deposition of aluminum microcrystal, but also the presences of semi-sphere aluminum microcrystal which rooted in the tip of micrometer-sized pores are observed. On the one hand, this extremely interesting phenomenon which the micrometer-sized pores are smoothed may be explained in terms of principle of electrochemical deposition; on the other hand, we have laid the formation mechanism of semi-spherical aluminum microcrystal at the door of Gibbs free energy.

Abstract: The primary aim of this communication is to introduce a novel approach of preparation of solar cell, viz. PS based solar cell, which is on the basis of the basic principle of the well established photovoltaic effect. We carefully investigate the current-voltage characteristics of the PS-based solar cell by virtue of performing the measurement of both current and voltage of PS-based solar cell under the condition of the sunlight irradiation and priori to sunlight irradiation in the purpose of observing clearly the photovoltaic effect possessed by the PS based solar cell. Judging by the results obtained in this paper, we can safely draw the conclusion that porous silicon is a good candidate material for the preparation of solar cell, that is to say that our study is giving high hope for the industrial production of high efficient PS-based thin film solar cells.

Abstract: We have investigated the photoluminescence (PL) of a porous silicon film in which a typical nematic liquid crystal 4-pentyl-4’-cyanobiphenyl infiltrated. Before the liquid crystal filtration, the PL spectrum of the porous silicon film is comprised of two luminescent bands, one of which is located at about 600 nm whereas the other of which is located at about 450 nm. After the liquid crystal filtration, the porous silicon film gives off intense deep-blue PL with its peak located at about 400 nm at the cost of the complete quenching of the PL from the original porous silicon film. Our results have demonstrated that the luminescent properties of porous silicon films can be dramatically modified by liquid crystal infiltration.

Abstract: In the present paper, we have not only investigated the top surface and cross-section morphology, but also measured photoluminescence spectra characteristic of porous silicon after deposition of metallic ions by electrochemical deposition employing scanning electron microscopy (SEM) and spectrometer, respectively. It is apparent from the SEM images that the microstructure of porous silicon is seriously ruined by the metallic ions deposited by electrochemical deposition. Most interesting is the finding that in the photoluminescence spectrum of porous silicon after the deposition of metallic ions such as AL3+ and Cu2+, the luminescence band gradually is quenched as the electrochemical deposition progressed. A careful consideration of the results obtained show that according to the basic theory of well-established quantum confinement model, the quenching of photoluminescence spectra of porous silicon may well be attributed to the microstructure fell into ruin. On the other side of the fence, we can interpret the physical origin of the phenomenon in view of the presence of metallic ions which give rise a series of energy level deep in the band gap of porous silicon.

Abstract: We have investigated the morphology and photoluminescence (PL) of Zinc Oxide (ZnO) and Zinc sulphide (ZnS) compound grown on porous silicon at room temperature. Under different excitation wavelengths (320 nm, 340nm, 370 nm), the photoluminescence (PL) spectra of PS-ZnS-ZnO composites were different, and at 550nm there is a strong photoluminescence peak. Energy dispersive spectroscopy (EDS) has been carried out to evaluate the existing of ZnO/ZnS compound. In addition, the scanning electron microscopy (SEM) observation shows that the morphology of the PS-ZnS-ZnO composites was well grown on porous silicon.

Abstract: Porous silicon (PS) of uniform structure was prepared by electroless silver deposition on surface of silicon at near room temperature in HF-AgNO3 system solution. Morphology of PS was characterized by scanning electron microscopy. The results showed that the diameter of hole was 1-2μm and holes distributed regularly. The ethylene diamine tetra acetic acid (EDTA) was an important additive to control the etching rate of silicon, which is of great significance to research the mechanism of porous silicon formation. Furthermore, photoluminescence property of PS was characterized.