Steiner Dov, Aharoni Assaf, Banin Uri, Millo Oded
Departments of Physics and Physical Chemistry and the Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Nano Lett. 2006 Oct;6(10):2201-5. doi: 10.1021/nl061410+.
The electronic level structure of colloidal InAs quantum dots (QDs) in two-dimensional arrays, forming a QD-solid system, was probed using scanning tunneling spectroscopy. The band gap is found to reduce compared to that of the corresponding isolated QDs. Typically, the electron (conduction-band) ground state red shifts more than the hole (valence-band) ground state. This is assigned to the much smaller effective mass of the electrons, resulting in stronger electron delocalization and larger coupling between electron states of neighboring QDs compared to the holes. This is corroborated by comparing these results with those for InAs and CdSe nanorod assemblies, manifesting the effects of the electron effective mass and arrangement of nearest neighbors on the band gap reduction. In addition, in InAs QD arrays, the levels are broadened, and in some cases their discrete level structure was nearly washed out completely and the tunneling spectra exhibited a signature of two-dimensional density of states.
利用扫描隧道光谱法探测了二维阵列中形成量子点 - 固体系统的胶体砷化铟量子点（QD）的电子能级结构。发现与相应的孤立量子点相比，带隙减小。通常，电子（导带）基态的红移比空穴（价带）基态的红移更大。这归因于电子的有效质量小得多，与空穴相比，导致更强的电子离域以及相邻量子点的电子态之间更大的耦合。通过将这些结果与砷化铟和硒化镉纳米棒组件的结果进行比较，证实了电子有效质量和最近邻排列对带隙减小的影响。此外，在砷化铟量子点阵列中，能级变宽，在某些情况下，它们的离散能级结构几乎完全消失，隧道光谱表现出二维态密度的特征。
