Electrostatic gates are of paramount importance for the physics of devices based on high-mobility two-dimensional electron gas (2DEG) since they allow depletion of electrons in selected areas. This field-effect gating enables the fabrication of a wide range of devices such as, for example, quantum point contacts (QPC), electron interferometers and quantum dots. To fabricate these gates, processing is usually performed on the 2DEG material, which is in many cases detrimental to its electron mobility. Here we propose an alternative process which does not require any processing of the 2DEG material other than for the ohmic contacts. This approach relies on processing a separate wafer that is then mechanically mounted on the 2DEG material in a flip-chip fashion. This technique proved successful to fabricate quantum point contacts on both GaAs/AlGaAs materials with both moderate and ultra-high electron mobility.
On-chip quantum sensing of Kondo spins in a high-mobility quasi-one-dimensional nanoconstriction
National Yang Ming Chiao Tung University（国立阳明交通大学）；National Cheng Kung University（国立成功大学）；University College London（伦敦大学学院）；National Taiwan University（国立台湾大学）；Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom（卡文迪许实验室）；Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom（谢菲尔德大学电子电气工程系）；Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan 701, Taiwan（国立成功大学量子前沿研究与技术中心）
