Fabrication of Quantum Wires Based on Selective Doping Mechanism and Its Application to Functional Devices Using Quantum Parallelism

我们的目标是建立我们独创的量子线制作方法，并进一步发展该方法应用于实现“量子器件”。我们除了在(100)GaAs衬底上生长量子线外，还研究了在(311)A衬底上生长的量子线的制备和电学特性。对量子线晶体管的低温温度测量显示出明显的量子线特性。主要结果描述如下。(I)建立了一种基于图案化衬底选择性掺杂机制的器件质量量子线的制备新方法。与电子束光刻或扫描探针法等先进的纳米光刻技术不同，本方法被证明能够在一次生长中加工出晶片尺度的精细结构。静电力显微镜显示，得到的量子线在结构上保持了沿毫米长的高质量。(Ii)单电子振荡器…在2K时，在夹断条件附近观察到更多的碰撞。温度和外部磁场的详细测量表明，沿量子线的电势起伏导致了一系列约6 meV深的孤立电势袋。目前的结果显示了基于本方法的毫米长量子线的限制势的平坦度。此外，我们还观察到了明显的电导振荡，这是77K和4K下一维电导的明显证据。这一结果有力地表明，在没有模式混合的情况下，在77K或更高的温度下实现了一维导电。(3)研究了单线晶体管的晶体管特性。在300K和77K下，1.5μm栅晶体管的跨导分别为580mS/mm和650mS/mm。这些结果属于基于GaAsAlGaAs调制掺杂晶体管的高端研究方向。这一结果表明成功地制备了高质量的一维电子系统。它还揭示了极小的栅漏电流，数量级为几十皮安培。与这种低泄漏特性相结合，本量子线方法被证明具有基于经典和量子泛函原理的集成量子量子晶体管电路的高潜力。较少

We have aimed at establishing our original fabrication methods of quantum wires and further developing the method to apply to the realization of the "quantum devices". We have investigated the fabrication and the electronic characterization of the quantum wires grown on facets on (311)A GaAs substrates in addition to the (100) GaAs substrates. Cryogenic temperature measurement on quantum wire transistors showed clear quantum wire characteristics. The major results are described below. (I) We have established a new fabrication methods of device quality quantum wires based on selective doping mechanism on patterned sustrates. Unlike the advanced nano-lithography technique such as electron beam lithography or scanning probe method, the present method was demonstrated to be able to process wafer scale fine structures in one step of growth. The obtained quantum wires were shown to maintain high quality along mm long structurally by Electrostatic Force Microscopy. (ii) Single electron oscill … More tion was observed near pinch-off conditions at 2K. Detailed measurements changing temperature and the external magnetic fields relealed that the potential ondulation along the quantum wire resulted in series of isolated potential pockets of 6meV or so deep. Present results shows degree of flatness of the confinement potential along the mm long quantum wires based on the present method. In addition, we have observed clear conductance oscillations which are clear evidence of 1-dimensional conduction at 77K and 4K. This result strongly indicates that one-dimensional conduction is achieved at up to 77K or more without mode mixing. (iii) Transistor characteristics of the "single wire" transistor were also investigated. The I .5μm gate transistor showed the transconductance of 580mS/mm and 650mS/mm at 300K and 77K respectively. These results belong to high end of the modulation doped transistors based on GaAs/AlGaAs. This result indicates successful fabrication of high quality one-dimensional electron systems. It also revealed extremely small gate leakage current of the order of tens of picoamperes. Together with this low leakage characteristics, the present quantum wire approach was shown to have high potentail of integrated quantum qire transistor circuits based on classical and quantum funcional principles. Less