Optic Character Of Porous Alumina And Low Dimension Nano-crystalline Silicon

Due to their surprising physical and chemical properties, nano-materials have significant potential applications in materials' intelligentization ,highly integration of components, highly density storage and ultra fast transportation. Therefore, the research on nanomaterials is flourishing. Porous alumina has typical self-organization structure .The dimension of pores is almost unanimous all over the membranes,the size and depth of pores can change according to preparation conditions.Porous alumina with its special nanometer structure pioneered a new way for the development of new-style function material. Silicon(Si) is the leading material of microelectronic devices, but the nature of indirect band gap of Si hinders its application in integrated optoelectronics. The preparation of low dimension nano-crystalline Si ,due to can adjust the band gap of body Si and make they emit supernal efficiency visible light, have received the people's attention in the near years.The first chapter was preface in the paper. In this chaper, the concept of nanometer and peculiar character of nanomaterial were discussed.The second chapter was about the prepartion of porous alumina. Samples were fabricated by anodization in traditional H2SO4 ,H2C2O4 and H3PO4,respectively.The structures of all samples were investigated by Scanning Electron Microscopy (SEM) observation. It was found that the dimension of pores is almost unanimous all over the membranes. The size and depth of pores can change according to preparation voltage and anodic time. It also founded that samples of porous alumina had excellent transmission in many wavelength ranges.In the third chapter, samples of porous silicon were fabricated by different current density. Porous silicon was dispersed into a colloid of Si nanoparticles by using supersonic. Photoluminescent properties of PS and Si nanoparticles were studied systematically. It was found that, with the incresing of the current density, the peaks of PL of PS occur the blue shift. As the same time ,the peaks of PL of Si nanoparticles also occur the blue shift, as well as intensity for peaks was enhanced, and observed a ultrabright blue-purple photoluminescent band.The results showed that the Quantum Confinement Effect and Surface layers were important for the PL spectra of porous silicon and Si nanoparticles. According to previous theories, it had been suggested that the photoluminescence originated from the quantum confinement effects and the luminescent centers in Surface layers covering the nanoscale silicon particles.In the fourth chapter, nano-crystalline silicon (nc-Si) films had been fabricated using high vacuum electron beam evaporation on porous alumina and silicon. After the processes of high temperature annealing, the Photoluminescence of nc-Si films were observed in the measurement temperature range of 10K~ 300K .In addition , several measuremental techniques, including Scanning electronic microscopy (SEM), X-ray diffraction (XRD) and infrared absorption (FTIR) were used to analyze the morphology characteristic ,crystalline phase and composition of the nc-Si films .The experimental results showed that with temperature increase ,the PL peaks have a red shift, while they have a blue shift in range of 50K~80K. The PL intensity decrease with temperature increase ,while they have a little increment in the range of 60K-80K. According to previous theories of the PL mechanism of nc-Si films ,it has been suggested that the photoluminescence originated from the quantum confinement effects and the luminescent centers in Surface layers covering the nanoscale silicon particles.In the fifth chapter ,the experiments mentioned above were summarized.