NCTS (South)


DATE2015-03-13

TIME14:10

PLACE物理二館地下室 (49X04)

FIELDOther

SPEAKER 林彥丞 - Ministry of Science and Technology & National Chiao Tung University

TITLECarrier Dynamics in Dilute II-VI Oxide Highly Mismatched Alloys

ABSTRACTRecently a new class of semiconductors has emerged, whose fundamental properties are dramatically modified through the substitution of a relatively small fraction of host atoms with an element of very different electronegativity and size, the so called highly mismatched alloys (HMAs). ZnSeTe, ZnSeO, and ZnTeO are the most widely studied examples of II-VI HMAs, exhibiting multiple band gaps and giant band gap bowing. The unusual electronic properties are well explained in the framework of the band anticrossing (BAC) model. According to this model, the electronic structure of the alloys is determined by the interaction between defect states introduced by the minority Te or O atoms and the extended states of the host semiconductor matrix. As a result the conduction or the valence band splits into two subbands (E+ and E-) with distinctly nonparabolic dispersion relations. This talk comprehensively introduces the unique electronic structures and carrier decay dynamics in ZnSeTe, ZnSeO, and ZnTeO HMAs, which are of great importance for fundamental science and of particular relevance to the energy conversion devices.
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