Nanometer-scale measurements of electronic states in InAs/GaAs quantum dots

Nanometer-scale measurements of electronic states in InAs/GaAs quantum dots
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InAs/GaAs 量子点中电子态的纳米级测量

DOI：
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发表时间：
2009
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影响因子：
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通讯作者：
Jouhahn Lee
Jouhahn Lee
中科院分区：
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文献类型：
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作者：
V. Dasika;R. Goldman;J. Song;W. Choi;N. Cho;Jouhahn Lee

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我们利用横断面扫描隧道显微镜（XSTM）和扫描隧道光谱（STS）的组合研究了单个（非耦合）量子点（QDs）和周围湿润层（WLs）中电子态的起源。XSTM图像显示长（短）轴为18±5nm（9±3nm）的不耦合椭圆型量子点。室温STS光谱显示量子点内的有效带隙存在梯度，在量子点核心和顶部表面附近的值最小。有效带隙的变化主要受铟成分梯度的影响，受量子点形状和应变的影响最小。铟成分梯度也主导了WL的有效带隙变化。
We have investigated the origins of electronic states in individual (uncoupled) quantum dots (QDs) and the surrounding wetting layers (WLs) using a combination of cross-sectional scanning tunneling microscopy (XSTM) and scanning tunneling spectroscopy (STS). XSTM images reveal uncoupled ellipse-shaped QDs with 18±5nm (9±3nm) major (minor) axes. Room temperature STS spectra reveal a gradient in the effective bandgap within the QDs with smallest values near the QD core and top surfaces. The variations in effective bandgap are apparently dominated by indium composition gradients, with minimal effects due to the QD shape and strain. Indium composition gradients also dominate the effective bandgap variations in the WL.