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首页> 外文期刊>Physical review >Temperature-dependent Midinfrared Photoluminescence Of Epitaxial Pbte/cdte Quantum Dots And Calculation Of The Corresponding Transition Energy
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Temperature-dependent Midinfrared Photoluminescence Of Epitaxial Pbte/cdte Quantum Dots And Calculation Of The Corresponding Transition Energy

机译：外延Pbte / cdte量子点随温度变化的中红外光致发光及其跃迁能的计算

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摘要

We present the temperature dependence of continuous-wave midinfrared photoluminescence of PbTe quantum dots in a CdTe matrix. The quantum dots are formed by epitaxial precipitation of a two-dimensional PbTe layer upon thermal annealing. A strong shift of the emission to longer wavelengths with decreasing temperature is found. This shift is not only caused by the strong temperature dependence of the band gap of PbTe but also by the strain in the dot as well as by the change in quantization energies, both being temperature dependent due to the thermal-expansion mismatch between PbTe and CdTe, and via the effective masses of PbTe. At low temperatures we observed an increase in the emission intensity with rising temperature, depending on dot size. This is attributed to the presence of a dark ground state, as was also observed for lead salt nanocrystals. The influence of the excitation power on the emission spectra at various temperatures indicates carrier redistribution between the dots. Furthermore, an analytical calculation of the ground-state transition energy in the dots is performed using a spherical dot shape, and including the temperature-dependent strain in the dots and the matrix as well as the temperature dependence of the effective masses of PbTe. From these model calculations, a good agreement to the experimental data is obtained over the whole temperature range from 20 to 300 K.
机译：我们提出了CdTe矩阵中PbTe量子点的连续波中红外光致发光的温度依赖性。量子点是通过在热退火时外延沉积二维PbTe层而形成的。发现随着温度降低，发射向较长波长的强烈偏移。这种偏移不仅是由于PbTe带隙的强烈温度依赖性引起的，而且还是由于点中的应变以及量化能量的变化而引起的，这两者都是温度依赖性的，这归因于PbTe和CdTe之间的热膨胀失配，并通过有效质量的PbTe。在低温下，我们观察到发射强度随温度升高而增加，这取决于点的大小。这归因于暗基态的存在，正如铅盐纳米晶体所观察到的那样。在各种温度下激发功率对发射光谱的影响表明了点之间的载流子重新分布。此外，使用球形点形状对点中的基态跃迁能量进行分析计算，其中包括点和基体中随温度变化的应变以及有效质量的PbTe随温度的变化。通过这些模型计算，可以在20至300 K的整个温度范围内获得与实验数据的良好一致性。

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