Electron Quantum Correlation in in Semiconductor Quantum-Dot lattice Structures

利用半导体二维电子系统揭示了量子霍尔效应和分数量子霍尔效应等重要的量子关联效应。在该系统中，还实现了在高速FET和激光器等实际器件中的应用。然而，在低维系统中，无论是基础研究还是器件应用都没有取得显著进展。一个主要原因在于其几何精度差。在二维结构中，每层的厚度具有原子尺寸精度。然而，在一维和零维结构中，侧壁相当粗糙。此外，自下而上的自组装过程产生的结构具有不均匀性和随机分布。因此，在本研究中，我们采用区域选择性外延结合电子束光刻和迁移增强外延。我们已经成功地用AlGaAs/GaAs、InAs/GaAs和InGaAs/GaAs制备了高质量的一维电子线和量子点晶格。纳米结构的原子级平坦侧壁通过利用微刻面结构形成。为了精确地制造出设计好的结构，横向生长应被最小化。这是通过优化碳纳米管沉积顺序来实现的。一维线具有弹道输运特性。二维量子点晶格表现出独特的输运特性。它们也被证明对二维光子晶体有用。

Important quantum correlation effects such as quantum Hall effect and fractional quantum Hall effect have been revealed using the semiconductor two-dimensional electron system. In this system, applications to practical devices such as high speed FETs and lasers have also been achieved. In the lower dimensional systems, however, no prominent progress has been achieved in both fundamental research and device applications. A major reason to this lies on their poor geometrical accuracy. In the two-dimensional structures, the thickness of each layer has atomic size accuracy. However, in one- and zero-dimensional structures, side walls are quite rough. Moreover, structures produced by bottom-up.self-assembly process suffer from inhomogeneity and random distribution. In the present research, therefore, we adopted area-selective epitaxy by combining with e-beam lithograph and migration-enhanced epitaxy(MEE). We have succeeded in fabricating high quality one-dimensional electron wires and quantum dot lattices with AlGaAs/GaAs, InAs/GaAs, and InGaAs/GaAs. Atomically flat side walls of nano-structures are formed by utilizing micro-facet structures. To fabricate accurately the structures with designed ones, lateral growth should be minimized. This has been accomplished by optimizing the MEE deposition sequence. One dimensional wires exhibit ballistic transport characteristics. Two dimensional quantum dot lattices show unique transport characteristics. They have proved useful also for two-dimensional photonic crystals.