The quantum confinement effect on the spectrum of near-field thermal radiation by quantum dots
The quantum confinement effect on the spectrum of near-field thermal radiation by quantum dots
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DOI：
10.1063/5.0049729
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发表时间：
2021-07
影响因子：
3.2
通讯作者：
Saman Zare;Sheila Edalatpour
中科院分区：
文献类型：
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作者：
Saman Zare;Sheila Edalatpour
研究了量子点（QD）周期性和随机阵列对近场热辐射光谱的量子限制效应。由三种铅硫属化物（即硫化铅、硒化铅和碲化铅）制成的 QD 阵列热发射的局部态密度 (LDOS) 在距阵列的近场距离处计算。通过利用优化技术从其吸收光谱中提取量子点的介电函数。热离散偶极近似用于计算 LDOS。结果表明，通过改变点的大小可以显着调节铅硫族化物量子点周期性阵列发射的近场 LDOS 峰值波数（高达 4490 cm）。 LDOS 与 QD 极化率的虚部成正比，该虚部在 QD 的带隙能量处达到峰值。 QD 的带隙能量（以及 LDOS 峰值）受尺寸相关的量子限制效应的显着影响。虽然量子点随机阵列的热辐射幅度与填充因子相同的周期性阵列的热辐射幅度可能相差 ±26%，但周期性阵列和随机阵列的 LDOS 谱和峰值位置是相同的。 QD阵列之间的近场辐射热传递的峰值波数也受到QD中的量子限制的强烈影响，因此可以通过改变QD的尺寸来调节。
The quantum confinement effect on the spectrum of near-field thermal radiation by periodic and random arrays of quantum dots (QDs) is investigated. The local density of states (LDOS) thermally emitted by QD arrays made of three lead chalcogenides, namely, lead sulfide, lead selenide, and lead telluride, is computed at a near-field distance from the arrays. The dielectric function of the QDs is extracted from their absorption spectra by utilizing an optimization technique. The thermal discrete dipole approximation is used for computing the LDOS. It is shown that the peak wavenumber of near-field LDOS emitted by periodic arrays of lead chalcogenide QDs can be significantly modulated (up to 4490 cm) by varying the size of the dots. The LDOS is proportional to the imaginary part of the QDs’ polarizability which peaks at the bandgap energy of the QDs. The bandgap energy of the QDs (and thus the LDOS peak) is significantly affected by the quantum confinement effect which is size-dependent. While the magnitude of thermal radiation by random arrays of QDs can be different from the periodic arrays with the same filling factor by up to ±26%, the LDOS spectrum and peak location are the same for both periodic and random arrays. The peak wavenumber of near-field radiative heat transfer between the QD arrays is also strongly affected by quantum confinement in the QDs, and thus it can be tuned by changing the size of the QDs.