论文标题
耦合的超薄CDTE/Znte量子井结构中的热激子松弛
Hot exciton relaxation in coupled ultra-thin CdTe/ZnTe quantum well structures
论文作者
论文摘要
CDTE/ZNTE不对称双量子井(QW)结构的光致发光(PL)和PL激发(PLE)光谱在一系列包含两个CDTE层的样品上研究了Znte矩阵中的2和4单一厚度(ML)的标称厚度。样品在Znte垫片的厚度上有所不同,CDTE QW在45、65和75毫升的厚度之间有所不同。已经发现,在烈性激发时,来自浅质量QW的PL在充分弱的激发强度下取决于热激子的重组。结果表明,在这些条件下,当PL被具有不同波长的激光激发时,随着热激子的初始动能的增加,来自浅层和深QW的PL强度的比率呈指数降低。发现具有LO声音发射的热激子的能量松弛确定了浅质量QW的PLE频谱的形状,在Znte BandGap上方高达20多个LO Phonons的激子动能范围内。我们已经表明,获得的结果通过QW之间的电荷模型和能量传递进行了很好的描述。
The photoluminescence (PL) and PL excitation (PLE) spectra of CdTe/ZnTe asymmetric double quantum well (QW) structures are studied on a series of samples containing two CdTe layers with nominal thicknesses of 2 and 4 monolayers (ML) in the ZnTe matrix. The samples differ in the thickness of the ZnTe spacer between CdTe QWs which is 45, 65 and 75 ML. It has been found that at above-barrier excitation the PL from a shallow QW at sufficiently weak excitation intensities is determined by recombination of hot excitons. It is shown that under these conditions, when PL is excited by lasers with different wavelengths, the ratio of the PL intensities from shallow and deep QWs decreases exponentially with an increase of the initial kinetic energy of hot excitons. It is found that energy relaxation of hot excitons with LO phonon emission determine the shape of the PLE spectrum of shallow QW in the range of exciton kinetic energies up to more than 20 LO phonons above ZnTe bandgap. We have shown that the results obtained are well described by the model of charge and energy transfer between QWs.