| Porous silicon (PS) is a new type silicon-based material developed in recent years, which has different properties compared with the crystalline silicon materials. Porous silicon can luminescence efficiently across the whole range from the near infrared, through the visible region, to the near UV region. This characteristic makes it possible to fabricate light-emitting devices and solve the key problem of the optoelectronic integrated circuit (OEIC), opening up the bright future for the very large integrated circuit (VLIC).Bulk silicon, with indirect band gap of 1.12 eV, doesn't emit visible light at room temperature. With a broad and likely direct band gap, porous silicon has a different band structure from that of the bulk silicon. Thus the porous silicon can emit visible light at room temperature. Several methods commonly used in preparing porous silicon have been represented. Photoluminescence and electroluminescence (EL) properties of porous silicon in literature are summarized. Qualitative description is given for the prevalent mechanisms proposed to explain the bright PL and EL.Firstly, the porous silicon was modified by surface chemical modifying. The PS was formed by photo-electrochemical means. Anodization was carried out on n-type silicon (111) substrates with resistivity (n+-n-Si: 3 Ω·cm - 5 Ω·cm n-Si: 80 Ω·cm -100 Ω·cm). The n+-n type PS ( 3Ω·cm -5 Ω·cm) had been immersed in the mixture of amine ((c2H5)3N : C2H4(NH2)2 =3:2) for twenty minutes, then immersed in the H2O2 solution for fourteen hours, with blowing dry, the modifying PS has emitted blue luminescence( max wavelength at about 422 nm) under a UV lamp. The n-type PS (80 Ω·cm-100 Ω·cm) had been immersed in the mixture of amine ((C2H5)3N :C2H4(NH2)2 =3:2) for twenty minutes, then carried on rapid thermal oxidation (RTO) through a quartz tube and oxidized in a floating oxygen ambience (0.5 L/min) at the temperature 400 ℃ for 30 s . The blue -white luminescence (max wavelength at about 455 nm) band can be observed under a UV lamp. The blue white luminescence was explained by the quantum confinement effect (QC) model.Secondly,the electrophoretic properties of porous silicon were studied. The orange-emitting as-anodized porous silicon was suspended in toluene by ultrasonic. The electrophoretic behavior of porous silicon (PS) suspended in toluene has been discovered and studied. It has been found that porous silicon particles drift inversely in the external electric field and adhere to the surface of positive electrodes, such as Pt, p+-Si, indium-tin oxide (ITO) coated glass etc. There is a linear relationship between the photoluminescence (PL) intensity and the PS concentration of the suspension. The influence factors on the PL intensities of the PS suspension, such as deposition time and applied electric field intensity, were examined in detail. The morphology of the deposited PS films and as-prepared PS has been measured using scanning electron microscope (SEM). X-ray photoelectron spectra (XPS) and Fourier Transform infrared (FTIR) have been used to analyze the deposited PS films.Thirdly, a new method of compositing ZnO nanometer particles was studied. The electrochemical reactions on a high pure Zn ( 99.999%) anode and a Pt cathode in ethanol at high voltage of 500 V/cm have been investigated in this paper. Growth of ZnO particles on the Pt cathode surface were observed by X-ray diffraction and electron diffraction pattern (EDP). The results show that the ZnO particles have wurtzite-type structure. The ZnO particles are excited by ultraviolet (UV) exciting light(365 nm), showing two photoluminescence ( PL ) peaks/bands , centered at 2.90 eV ( blue ) and 2.23 ~ 2.41 eV ( yellow-green ), respectively. The intensity of the yellow-green band was reduced after the product had been annealed in N2 and O2 at 350 C for 1h. Ultraviolet visible absorption spectrum shows that the ZnO absorbs ultravioletlight intensely. The mechanism of ZnO formation and photoluminescence is tentatively analyzed.Lastly, Por...
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