Photoluminescence And Photoconductivity Characteristics Of Hydrothermally Etched Porous Silicon

The discovery of visible photoluminescence (PL) at room temperature from electrochemically etched porous silicon (PS) in 1990 by Canham has generated great research interests in nanocrystalline (nc-Si) structures due to their possible applications in optoelectronic integration. Today, electrochemical anodization is still a universal method that used in preparing porous silicon. Unfortunately, till nowadays, the stability of photoluminescence of PS as well as the large-scale PS preparation remains unsolved. In order to get through this handicap for more practical utilization of PS, a method called hydrothermal etching was first introduced to the preparation of PS in 1996 by the University of Science and Technology of China. Since the characteristics of porous silicon relate closely to the parameters - including sorts of solutions, etching time, temperature and so on - that used in hydrothermal etching, much more research must be done to get futher understandings of them. So in this thesis, we prepared a series of iron-passivated porous silicon (IPS), and studied their photoluminescence properties and photoconductivity characteristics, the possible mechanisms were also discussed.In the first part of this thesis, the photoluminescence properties of iron passivated porous silicon which was fabricated by hydrothermally etching the boron-doped (4-6 Ω·cm), (111) oriented single crystalline silicon wafers were mainly studied. The morphologies, photoluminescences (PL), Fourier transform infrared transmittance spectra of the IPSs prepared under different etching conditions were investigated as well. And a phenomenological simulation called Islam-Kumar model was used to calculate the nanocrystalline size distributions in porous silicon. Besides, the dependence of PL spectra on radiation time under 250 nm ultraviolet, as well as the PL peak energies on the excitation wavelength were recorded with the Fluorescence Spectrophotometer. All of them arrived at the following conclusions.1. The morphologies were different from sample to sample, and no obvious relationships between the morphologies and etching condition could be found.2. Since light emitting of porous silicon is originated from the nanocrystals that smaller than the exciton Bohr radius in bulk Si (~5 nm), it is difficult to deduce a close relation between the...