Shang-Fen Ren's Research Expertise


Extensive research experience on electronic, optical, and vibrational properties of semiconductors, semiconductor surfaces, and low dimensional semiconductor systems. Recent research focused on the quantum confinement effect of phonon modes in low-dimensional semiconductor systems, including interface modes, mode mixing due to the reduction of dimensionality, and the quantum confinement effect of phonon modes with different symmetries in semiconductor quantum dots.


Most Recent Research Interest


In recent years, Ren and her co-workers have developed a microscopic valence force filed model to study phonon modes in semiconductor QDs with up to about 12,000 atoms (about 8.5 nm in size). The uniqueness of this model is that the projection operators of the irreducible representations of the group theory are employed to reduce the computational intensity. By using this method, all the vibrational frequencies and vibrational strengths can be calculated directly from the dynamic matrices in five different irreducible representations. Not only this allows the investigation of all the microscopic detail of phonon modes in QDs with a much larger size, but also it allows the investigation of phonon modes in QDs with different symmetries. These investigations lead to many interesting physics that otherwise can not be revealed. At present, Ren and her co-workers are further applying the results of this microscopic model to investigate other related physical properties of QDs, such as the Raman scattering, the electron-phonon interaction, the carrier relaxation, and the light emission of QDs.