Identification of atomic-like electronic states in indium arsenide nanocrystal quantum dots
Identification of atomic-like electronic states in indium arsenide nanocrystal quantum dots
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作者：
Banin, U;Cao, YW;Millo, O
半导体量子点，由于它们的小尺寸，标志着分子和固态制度之间的过渡，通常被描述为“人造原子”（参考文献1-3）。这种类比起源于半导体纳米晶体中量子限制效应的早期工作，其中电子波函数被预测（4）表现出类似原子的对称性，例如's'和'p'。量子点的光谱研究已经证明了离散的能级结构和窄的跃迁线宽（5-9），但离散态的对称性只能间接推断。在这里，我们使用低温扫描隧道光谱直接识别具有s和p字符的一系列砷化铟纳米晶体中的类原子电子态。这些状态在隧穿电流-电压测量中分别表现为两重和六重单电子充电多重态，并且它们遵循类似原子的连续能级占据的Aufbau原理（10）。
Semiconductor quantum dots, due to their small size, mark the transition between molecular and solid-state regimes, and are often described as 'artificial atoms' (refs 1-3). This analogy originates from the early work on quantum confinement effects in semiconductor nanocrystals, where the electronic wavefunctions are predicted(4) to exhibit atomic-like symmetries, for example 's' and 'p'. Spectroscopic studies of quantum dots have demonstrated discrete energy level structures and narrow transition linewidths(5-9), but the symmetry of the discrete states could be inferred only indirectly. Here we use cryogenic scanning tunnelling spectroscopy to identify directly atomic-like electronic states with s and p character in a series of indium arsenide nanocrystals. These states are manifest in tunnelling current-voltage measurements as two- and six-fold single-electron-charging multiplets respectively, and they follow an atom-like Aufbau principle of sequential energy level occupation(10).