Optical and Structural Properties of Zn–Cd–Mn–Se Double Quantum Well Systems

Abstract

Double quantum well (DQW) structures consisting of a ZnCdSe well and a ZnCdMnSe well separated by a ZnSe barrier are grown with molecular beam epitaxy (MBE). The DQW structures are characterized by using X-ray diffraction measurement and simulation. Thickness of each well layer is designed so that the lowest energy level of ZnCdMnSe well is close to the excited level of the ZnCdSe well. Optical properties of the DQWs are studied with photoluminescence (PL) and reflection spectra in external magnetic fields up to 8 T in the Faraday geometry. Exciton transfer from ZnCdMnSe well to ZnCdSe well is observed in magneto PL with energy selective photoexcitation. Exciton energies in ground and excited states are estimated from PL excitation spectra and reflection spectra.

Relaxation dynamics of nonresonant excitation transfer processes assisted by coherent phonon environment

“…Here, the phonon system is assumed to be nondispersive, based on the experimental confirmation that LO phonons play a major role in this phenomenon. 5,8) Additionally, Refs. 9, 10, 15, and 16 suggest that the optical phonon system can be effectively represented by single-mode phonons.…”

“…[1][2][3][4][5][6][7] Spin-dependent ET phenomenon in semiconductor double QWs have also been reported, where longitudinal optical (LO) phonons assist non-resonant ET as a local environment. 5,6,[8][9][10] While phonons typically destroy coherence and dissipate the energy of the system, recent studies on nanoscale systems have revealed that phonons can assist transport, coherent manipulation, and entanglement generation. 4,[11][12][13][14] Furthermore, the mechanism of the non-resonant ET phenomenon has been theoretically investigated, 5,15,16) which has revealed that ET between twolevel systems (TLSs) can be considerably enhanced by synchronizing the phase and energy between TLSs and the dynamic phonon systems as local environments.…”