||In this thesis, we study two types of nanoscale electronic devices, single-electron devices and quantum point contact (QPC) formed in two-dimensional electron gas (2DEG). The system of single-electron devices we study is composed of a single-electron transistor (SET) and a single-electron box (SEB). The 2DEG devices are provided by Professor Jeng-Chung Chen research group in the National Tsing Hua University.|
In a SET, a central island connects to source and drain electrodes through two tunnel barriers. As the structure is made in nanoscale, charging energy is large, and Coulomb blockade effect should be pronounced. To perform the experiments, we placed the devices in a helium dilution refrigerator to reduce the thermal fluctuation effect. The current of SETs will be affected by surrounding electric potential. Therefore, by capacitively coupling a SET to a SEB, we can detect the charge tunneling events in the SEB by reading the current in the SET. In the thesis, we study all-aluminian and aluminian-palladium SETs, analyze fabrication process, parameter, and finally fabricate workable Single-Electron Devices.
The 2DEG we study is formed in heterojunction between GaAs and AlGaAs, we succeed to form QPC and observe quantized conductance. The conductance of QPC is affected by surrounding electric potential and we utilize as a Charge sensor to observe the charge transport behavior in quantum dots .
In this study, we successfully observe single electron tunneling events in both Single-Electron boxes and 2DEGs quantum dot by utilizing SETs and QPC , respectively , as charge sensors.
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