ABSTRACT
Gil-Ho Kim Department of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon 440-746, Korea Chi-Te Liang Department of Physics, National Taiwan University, Taipei 106, Taiwan D. R. Hang Department of Materials Science and Optoelectronic Engineering, National Sun Yat-sen University, Kaohsiung 804, Taiwan Institute of Materials Science and Engineering, National Sun Yat-sen University, Kaohsiung 804, Taiwan C. F. Huang National Measurement Laboratory, Center for Measurement Standards, Industrial Technology Research Institute, Hsinchu 300, Taiwan D. A. Ritchie Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom
Abstract. We report the observations of the insulator-quantum Hall transitions in a gated two-dimensional (2D) GaAs electron system with self-assembled InAs dots. Transitions separating the insulator from the quantum Hall states of the filling factors v= 2 and 1 are observed at low and high magnetic fields, respectively. It is shown that these two transitions are equivalent although the difference between the low-field and high-field insulators is obvious in such a system. 1
1. Introduction Localization effects due to the quantum interference are important to the transport properties of the two-dimensional electron systems (2DESs) at low temperatures. [1-3] Insulating behaviors due to the zero-field localization have been observed in samples with high disorder. By applying a magnetic field B perpendicular to a 2DES, localization effects can result in the appearance of the quantum Hall effect. [4] According to the global phase diagram (GPD) constructed by Kivelson, Lee, and Zhang, [1] there is an insulating phase in addition to the quantum Hall (QH) states. The insulating behaviors at zero field, in fact, may correspond to such a phase. To enter a QH liquid from the insulator, a 2DES is expected to undergo an insulator-quantum Hall (I-QH) transition. In
this paper, we report an experimental study on such a transition observed in a twodimensional (2D) GaAs electron system with self-assembled InAs quantum dots.
