多量子阱中激子作为中间态的喇曼散射微观理论

Microscopic Theory for Raman Scattering Multiple Quantum Wells Mediated by Exciton States

鉴于准二维激子在半导体多量子阱的光学过程中所起的决定性的作用,可以预期,在共振喇曼散射中,激子应是主要的中间态。但由于多量子阱电子结构、激子、声子的研究只是在近几年才有比较深入的理解,迄今尚无系统的喇曼散射的微观理论。本文将给出二维各向同性近似和电偶极近似下的多量子阱喇曼散射微观理论。

A microscopic theory on resonant Raman profile and Raman phonon spectra mediated by exciton states in multiple quantum -wells (MQW) is presented. The theory takes proper account of effect of heavy-and light-hole mixing on the exciton states, and adopts an appropriate formula for electron-phonon interaction. The selection rule on exciton-LO-phonon scattering in MQW is summarized, revealing the role played by intrasubband and intersubband exciton Raman scattering. Numerical calculations show the dependence of exciton-phonon scattering on the well width and the dependence of the strength of Raman phonon peak on the modes and the incident energy. The mechanism for the asymmetry of the incoming and outgoing resonance is discussed.