Quantum point contact and quantum dot fabrication and measurement in two-dimensional electron gas

• Main Authors: Yen-Hao Huang, 黃彥豪
• Other Authors: Yung-Fu Chen
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/ymqk3h

碩士 === 國立中央大學 === 物理學系 === 106 === In this study, we used GaAs/AlGaAs heterostructure and monolayer MoS2 to construct two dimensional electron gas. We tried to fabricate double quantum dot structure on GaAs/AlGaAs heterostructure and measure the coplanar waveguide resonator coupling the two level system which consist of double quantum dot or not. This topic is related to circuit quantum electrodynamics. The recently progress is still in fabrication. Resonator and double quantum dot system completed separately. We must solve alignment fail and lift-off fail before measuring. On the other hand, we used a pair of the top-gate to fabricated quantum point contact device on monolayer MoS2 two dimensional electron gas. Top-gate vertex spacing is the width of the quantum point contact device channel. Top-gate line-width is the length of the quantum point contact device channel. In order to drive electrons out of the two dimensional electron gas near the top-gate range at -10V, we design the top-gate spacing below 100 nm. The electron beam lithography made the width of the top-gate line as narrow is about 60 nm, we used solid polymer electrolyte gate upgrade the carrier density on MoS2 surface so that the mean free path of electrons in the system can exceed 60 nm. We used current annealing to reduce the contact resistance in device, making smaller resistance in measurement. In order to reduce the thermal fluctuation, the measurement temperature was 50mK. We observed similar conductance quantization by constant current measurement.