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HL: Halbleiterphysik

HL 9: Poster I

HL 9.34: Poster

Montag, 27. März 2006, 15:15–17:45, P3

Energy transfer processes between extended band states and Te-related localized states in ZnS_1−xTe_x — •T. Niebling, P.J. Klar, and W. Heimbrodt — Dept. Physics and WZMW, Philipps-Univerisity of Marburg, Germany

Various wurtzite ZnS_1−xTe_x bulk samples of low x have been studied by time-resolved photoluminescence (PL). The dependence on concentration, on temperature, and on excitation density as well as the temporal behaviour indicate that the dynamics of the PL is influenced by excitation transfer processes between band states and the isoelectronic impurity levels located above the top of the valence band. These states can be related to Te_n complexes where n = 1, 2, 3 is the number of Te impurities forming the complex. For higher Te concentrations or immediately after the excitation pulse, the PL spectrum is dominated by a UV band whose intensity shifts towards a blue band either with increasing concentration or with increasing time delay after the excitation pulse. The observed concentration dependence is a manifestation of the statistics of the different complexes where preferably higher Te clusters occur with increasing x. The time evolution of the PL is caused by excitation transfer processes towards smaller energies. The energy transfer from the isolated centres to the pair states will be discussed in detail.