实际低维微结构拉曼散射理论

A theoretical model of Raman scattering lineshap is formulated in low-dimensional semiconductor structures, in which defects and impuries inevitably exist. In this model, because of the relaxation of the momentum conservation law, the Raman lineshape is determined by two factors, i.e. the density states of phonon modes and the interaction matrix elements. Thus a model of phonon density of states enhanced by Fr?hlich-interaction is used to clarify the origin of the Raman lineshape in GaAs/AlAs superlattices, which has recently been assigned to dips due to anticrossing of interface modes with the odd-order confined modes, rather than the peaks with the even-order modes. The numerical results based on this model have well reproduced main features in the resonant Raman spectra of superlattices with identical well-width but different barrier-widths, and unambiguoursly show that, instead of the dips, the even-order confined GaAs modes and interface modes are responsible for the Raman spectra in superlattices in the presence of imperfections. The model is also adopted to the Raman spectra in one-dimensional SiC nanorods. It has succeeded in explaining a 40 cm-1 Raman shift for LO modes in SiC-nanorod and predicting an unexpected 864 cm-1 peak which was later resolved in experiments. Besides, phonon modes in several novel quantum structures are calculated, such as quantum dots, the finite superlattice embedded in a microcavity, and the isotope rbonnanotube.

实际的低维微结构样品含有较多的缺陷.在申请者已建立的半导体准二维结构拉曼散射微观砺酆偷臀峁股幽Ｊ嚼砺鄣幕∩?在对碳化硅纳米棒拉曼实验成功解释的基础上,拟发挂桓鱿低忱砺垩芯渴导实臀⒔峁寡罚òǜ髦至孔酉摺⒘孔拥悖┑睦⑸洹Ｌ乇鹨吻迨导拾氲继宄Ц窭椎幕疚侍猓烤故怯晒庋臃寤故怯赏莨钩伞