THERMALIZATION OF FREE-EXCITONS IN ZNSE QUANTUM-WELLS

The thermalization dynamics of hot free excitons in ZnSe quantum wells is studied by photoluminescence excitation (PLE), steady-state (cw-PL ) and time-resolved photoluminescence (TRPL). Formation of excitons by emission of LO phonons is very efficient and leads to the generation of narrow hot-exciton distributions. The LO phonon-assisted recombinat ion of the excitons is a direct monitor of the hot-exciton dynamics. A thermalized exciton distribution is reached only after some 100 ps du e to the slow exciton relaxation assisted by acoustic phonons. The hot -exciton features in PLE, cw-PL and TRPL are consistently reproduced b y explicitly calculating the relevant scattering processes. (C) 1998 E lsevier Science B.V. All rights reserved.