Intersublevel Spectroscopy on Single InAs-Quantum Dots by Terahertz Near-Field Microscopy
Intersublevel Spectroscopy on Single InAs-Quantum Dots by Terahertz Near-Field Microscopy
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DOI：
10.1021/nl302078w
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发表时间：
2012-08-01
期刊：
影响因子：
10.8
通讯作者：
Helm, Manfred
中科院分区：
文献类型：
--
作者：
Jacob, Rainer;Winnerl, Stephan;Helm, Manfred
利用散射型近场红外显微镜结合自由电子激光，研究了埋层单InAs量子点的次能级间跃迁。实验在室温下进行掺杂的自组装量子点覆盖70 nm的GaAs层。当入射束的光子能量与子能级间跃迁能量（即限制在点中的导带电子的p-d和s-d跃迁）相匹配时，可以观察到单个点的清晰近场对比度。在中红外范围内观察到的这些共振的室温谱线宽度为5-8 meV，显着低于量子点系综的非均匀加宽谱线。该实验通过展示100 nm量级探针体积中单个电子的束缚到束缚跃迁信号，突出了近场显微光谱的强度（3）。
Using scattering-type near-field infrared microscopy in combination with a free-electron laser, intersublevel transitions in buried single InAs quantum dots are investigated. The experiments are performed at room temperature on doped self-assembled quantum dots capped with a 70 nm GaAs layer. Clear near-field contrast of single dots is observed when the photon energy of the incident beam matches intersublevel transition energies, namely the p-d and s-d transition of conduction band electrons confined in the dots. The observed room-temperature line width of 5-8 meV of these resonances in the mid-infrared range is significantly below the inhomogeneously broadened spectral lines of quantum dot ensembles. The experiment highlights the strength of near-field microspectroscopy by demonstrating signals from bound-to-bound transitions of single electrons in a probe volume of the order of (100 nm)(3).