Browsing by Author "Kim, Gil-Ho"

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Crossover from negative to positive magnetoresistance in a Si delta-doped GaAs single quantum well
(2010-07-01)
Lo, Shun-Tsung
;
Chen, Kuang Yao
;
Su, Yi-Chun
;
Liang, C. -T.
;
Chang, Y. H.
We have performed magnetoresistance measurements on a Si delta-doped GaAs single quantum well With increasing temperature T, a crossover from negative magnetoresistance (NMR) to positive magnetoresistance (PMR) can be observed Our experimental results suggest that such a crossover corresponds to a transition from variable range hopping regime to activated electron transport. This is also consistent with the measured non-monotonic carrier density dependence on T. (C) 2010 Elsevier Ltd All rights reserved.
On the direct insulator-quantum Hall transition in two-dimensional electron systems in the vicinity of nanoscaled scatterers
(2011)
Liang, Chi-Te
;
Lin, Li-Hung
;
Chen, Kuang Yao
;
Lo, Shun-Tsung
;
Wang, Yi-Ting
A direct insulator-quantum Hall (I-QH) transition corresponds to a crossover/transition from the insulating regime to a high Landau level filling factor nu > 2 QH state. Such a transition has been attracting a great deal of both experimental and theoretical interests. In this study, we present three different two-dimensional electron systems (2DESs) which are in the vicinity of nanoscaled scatterers. All these three devices exhibit a direct I-QH transition, and the transport properties under different nanaoscaled scatterers are discussed.