Yue Zhao

PHOTOLUMINESCENCE, COMPOSITION AND MICROSTRUCTURE OF POROUS SILICON PREPARED BY DIFFERENT SUBSTRATES

In this paper, the microstructure of porous silicon was discussed by scanning electron microscopy and Raman spectra. The compositions of the samples were studied by X-ray diffraction and electron diffraction. The luminescent properties of porous silicon were explored by the PL measurements. The results showed that the structure of the top porous silicon prepared by epitaxial silicon consists of meso-pores and that of the underlying porous silicon consists of macro-pores. Furthermore, the structure of porous silicon prepared by heavily doped silicon is made of nano-pores. The composition of porous silicon consists of the single-crystal phase, poly-crystal phase and amorphous-crystal phase, respectively. In addition, the luminescence of porous silicon may come from the defects on the silicon-rod surface and in Si complexes including siloxene, Si oxide and Si hydrides, and may not be related to amorphous phase and nano-phase.

STUDY OF OPTICAL PROPERTIES OF POROUS SILICON PRODUCED BY METAL-AID

We presented fluorescence spectra and cathode-luminescence spectra of as-prepared porous silicon under different preparation conditions. The luminescence of porous silicon may be related to the luminescent centers on porous silicon surface. The luminescent efficiency depended on the porosity of porous silicon, which further depended on the oxidative level of porous silicon with metal assistance. Under back illumination, the higher the oxidative degree of the metal is, the higher is the porosity and the luminescent efficiency of porous silicon. But under front illumination, the results exhibited an opposite tendency, which can be explained by the formation theory of PS.