Structural and Optical Characterization of a Quantum Wire

利用分子束外延（MBE）技术，在GaAs（110）面上自然形成了GaAs量子线，这些量子线的形成是由于在GaAs（110）面的巨台阶边缘形成了相干排列的巨生长台阶和GaAs层的可标记厚度调制。透射电子显微镜（TEM）、原子力显微镜和光致发光（PL）测量一致地证实了量子线的形成。虽然在这些量子线中观察到了平行于线方向的强偏振的PL，但是PL仍然很宽，这被认为是由于量子线结构的不均匀性。为了提高均匀性，我们采用了两步生长和生长中断的方法。为了了解单根量子线的发光特性，我们进行了微区荧光和扫描阴极荧光的测量。观察到单量子线的尖锐发光峰。我们还在具有巨台阶的邻位（110）面上生长了InAs和InGaAs层，发现在巨台阶边缘形成了InAs和InGaAs量子线和量子点。

We have demonstrated that GaAs quantum wires were naturally formed on vicinal GaAs (110) surfaces misoriented toward (111) A using MBE.These naturally formed quantum wires were induced by the formation of coherently aligned giant growth steps and temarkable thickness modulation of GaAs layrs at giant step edges. Transmission electron microscopy (TEM), atomic force microscopy and photoluminescence (PL) measurements consistently confirmed this formation of quantum wires. Although the PL strongly polarized parallel to the wire direction was observed for these quantum wires, the PL was rether broad and is thought to be due to the nonuniform quantum wire structures. To improve the uniformity, we employed the two-step growth and growth interruption method. More red-shifed and narrower PL peaks were abserved, indicating the thicker GaAs layrs at the step edges and the improved uniformity of the quantum wire structures.In order to know the luminescence from single quantum wires, we carried out micro-PL and scanning cathodoluminescence measurements. Sharp luminescence peaks were observed for single quantum wires. These sharp peaks are considered to come from the localized excitions.We also grow InAs and InGaAs layrs on the vicinal (110) surfaces with giant steps and found that InAs and InGaAs quantum wires and dots were formed at the giant step edges.