| Summary: | 碩士 === 國立彰化師範大學 === 光電科技研究所 === 95 === Self-assembled CdTe/ZnSe quantum-dot (QD) structures, which have a CdSe-like precurse-layer between CdTe quantum dots and ZnSe matrix, were grown by molecular beam epitaxy.
The optical properties and carrier dynamics of self-assembled CdTe/ZnSe QD structures was studied by photoluminescence (PL), photoluminescence excitation (PLE), and time-resolved photoluminescence (TRPL) measurements.
The cross-sectional transmission electron microscopy and PL measurements reveal the existence of a CdSe-like two-dimensional precursor layer (PCL) . The carrier dynamics of the structures was studied by PL and TRPL measurements. The temperature-dependent PL spectra revealed that there is a carrier transformation from small dots to larger dots via the precursor layer. Temperature- and power-dependent PL and PLE measurements verify the existence of the QD excited excitonic state in 5.0 mono-layer (ML) coverage. the life time of different QDs.
In 0.6 ML coverage, the TRPL spectra exhibited a double-exponential decay process, as the detection energy at PCL emission energy. The faster decay time is corresponded to the carrier lifetime in PCL. In 5.0 ML coverage, a faster and slower decay time represents the carrier lifetime in QD excited state for larger QD and the carrier lifetime in QD ground state for smaller QD.
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