Formation and Characterization of High Density Semiconductor Quantum Dots

我们发展了一种通过选择性区域金属有机气相外延（SA-MOVPE）生长来形成位置和尺寸可控的量子线（QWR）和量子点（QD）的技术。该技术适用于直接制造单电子晶体管和电路使用QD-QWR耦合结构。该项目的主要成果概述如下。(1)我们研究了SA-MOVPE制备高密度量子点阵列的机制。我们发现并阐明了自限机制在SA-MOVPE的顶部尺寸和形状的GaAs金字塔结构和脊结构的形成后，这样的三维结构保持。这种自限生长模式被用来实现量子点的尺寸均匀性。我们还阐明了GaAs金字塔的顶部尺寸是由台阶边缘吸附原子的吸附与脱附平衡决定的，并可由生长条件控制。(2)基于织物 ...更多信息 利用量子点阵列的光电子耦合技术，我们提出并成功地用SA-MOVPE方法制备了量子点和量子阱的二维耦合阵列，光学表征证实了量子点和量子阱的网络状阵列的形成。结果表明，我们提出的制造方法是有效的，以实现高密度集成的量子器件，如单电子晶体管，为未来的电子学。(3)利用SA-MOVPE技术形成的QWR-QD-QWR耦合结构与肖特基栅技术相结合，成功地制备了单电子晶体管。我们已经成功地实现了单电子反相器的电路工作，该反相器集成了量子线晶体管和单电子晶体管，量子点器件具有很强的横向约束，这对探索纳米结构的物理特性，如量子点中的近藤效应是有益的。少

We have developed a technique to form position-and size-controlled quantum wires (QWRs) and quantum dots (QDs) by selective area metalorganic vapor phase epitaxial (SA-MOVPE) growth. The technique is applied for the direct fabrication of single electron transistors and circuits using QD-QWR coupled structures. Main results of the project are summarized below.(1) We investigated the mechanism of SA-MOVPE for the fabrication of high-density QD arrays with extreme uniformity. We have found and clarified the self-limited mechanism in SA-MOVPE where the top size and shape of the GaAs pyramidal structures and ridge structures are maintained after the formation of such 3-dimensional structures. This self-limited growth mode is utilized to achieve size uniformity in QDs. We also have clarified that the top size of the GaAs pyramid is determined by the balance between the adsorption and desorption of adatoms at the step edges and can be controled by the growth conditions.(2) Based on the fabric … More ation technique of QD arrays, we have proposed and succes sfully fabricated a two-dimensional coupled array of QDs and QWRs by SA-MOVPE.The optical characterization has confirmed the formation of network-like array of QDs and QWRs. The results indicate that our proposed fabrication method is effective to realize high-density integration of quantum devices, such as single electron transistors, for future electronics.(3) Single electron transistors have successfully been fabricated by the combination of coupled structures of QWR-QD-QWR formed by SA-MOVPE technique and Schottky gate technology. We have succeeded in the demonstration of the circuit operation of single electron inverters, which integrates quantum wire transistor and single electron transistors fabricated by one-step growth on designed masked substrate for SA-MOVPE.Our quantum dot devices also have shown to exhibit strong lateral confinement that are beneficial to explore the physics of nanostructures, such as Kondo effect in QDs. Less