Dissertation > Mathematical sciences and chemical > Physics > Semiconductor physics > Semiconductor Properties of > Optical Properties

Silicon-Based Nanocrystal Light-Emitting Material

Author XuShaoHui
Tutor HouXiaoYuan
School Fudan University
Course Condensed Matter Physics
Keywords Porous silicon Pulsed electrochemical etching Transfer matrix method Microcavities Photonic crystal Quantum-well
CLC O472.3
Type PhD thesis
Year 2003
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In this thesis, the idea of photonic crystal has been introduced to the porous silicon material and a possible way to produce a porous silicon laser is presented: Lasing would be possible from localization of the photons in the structures of porous silicon photonic crystal. Along the main direction, one- and two-dimensional porous silicon photonic crystal structures have been investigated.I Porous silicon multilayers and mirocavities have been studied systematically, including theoretical calculations and experimental preparation.First, porous silicon mirocavities have been prepared by a pulsed electrochemical etching method. Orthogonal experimental method has been adopted to optimize the experimental conditions for fabrication of porous silicon mirocavities. Under the optimal condition, the full width at half maximum of the light emission peak is reduced to be 6 nm. A dynamic etching model based on diffusion of HF acid explains the experimental results well. It indicates that the narrow emission peak of porous silicon mirocavities prepared by the pulsed electrochemical etching method can be attributed not only to longitudinal etching, but also to transverse etching (soaking etching) of HF.Second, Porous silicon multilayers and microcavities prepared by the pulsed electrochemical etching method exhibit a variety of reflectivity and photoluminescence spectra. Comparison of the results measured with those calculated based on the transfer matrix method and quantum-box model reveals that the variation of the spectra can be attributed to the change in wavelength position of the stop-band of distributed Bragg reflectors and maximum of the broad light emission of porous silicon.Third, double microcavities with different period numbers of the middle mirror have been explored both theoretically and experimentally. The theoretical investigation indicates that the coupled modes will not exist when the period number of the middle mirror is twice as that of the outer mirrors. It is expected that the interaction between two photonic atoms is similar to that of the real atoms if one cavity can be regarded as a photonic atom with one orbital (S). The double microcavites can be regarded as a photonic molecule consisting of two photonic atoms, similar to H2+. Electric field analyses prove that is the case. In the experimental aspect, the porous silicon double microcavities with different period numbers of the middle mirror have been prepared by the pulsed electrochemical etching method. The samples are investigated by room temperature photoluminescence and reflectivity measurements. Double narrow-line light emission peaks have been observed in the visible and infrared region.II The porous silicon photonic quantum-well structures have been presented and studied systemically, including the theoretical calculation and experimental preparation.First, one-dimensional photonic quantum well structures operating in visible frequency region have been fabricated by sandwiching a different photonic crystal between two photonic barriers. Appearance of that the quantized confined photonic states in the band gap of the photonic barrier have been observed in both reflectance and transmission spectra, owing to the photon confinement effect. It is found that the confiner the electric field, the sharper the peak width. The different confined statescorrespond to the different oscillation modes, which can be well described by the resonant tunneling effect used in the semiconductor quantum well structures. It is found that the number of the confined states depends on the number of the periods adopted in the well photonic crystal. Thus, increased confined photonic states can be created simply by increasing the number of the periods of the well PC in the structures. Second, a new consideration for the photonic system of one-dimensional single and double photonic quantum well structures is described. It turns out that a photonic quantum well structure can be considered as a "photonic atom" with different photonic energy levels, simi

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