反量子點深嵌於一維系統中電子傳輸性質之研究

Electronic transport properties in 1D wire with an embedded antidot

吳佩蓉(Pei-Jung Wu)

指導教授 ： 林怡萍

國立清華大學/理學院/物理學系/碩士(2007年)

摘要

We have studied the phenomena of electronic transport in a quasi one-dimensional (1D) channel with an embedded antidot. The 1D channel is defined by either a set of split gates or ring gates, with a 100-nm-in-diameter antidot in the center. The presence of an antidot in the channel force electrons to split their paths, which then merge after the antidot. Such interference of their wave functions will change the normal transport behaviors of 1D electron gas. The two terminal magneto-conductance measurements taken at 0.3 K have shown intriguing yet different features under these two geometries. We observed inference patterns by controlling the gates separately, which can be suppressed after certain magnetic fields applied normal to the sample surface. Our devices also provide the opportunity to modulate electron modes from two paths and to study the tunable Aharonov-Bohm effect. In the current configuration we cannot detect the resonant tunneling of edge states via the embedded anitdot, which has been proposed for spin-filtering application. To further understand the physics behind the interference patterns, possibilities and limitation in device application, a refined measurement set-up at a lower temperature is needed.

關鍵字

Q1D ； QPC ； GaAs/AlGaAs ； antidot ； magneto-conductance ； Aharonov-Bohm effect (AB effect)

並列摘要

We have studied the phenomena of electronic transport in a quasi one-dimensional (1D) channel with an embedded antidot. The 1D channel is defined by either a set of split gates or ring gates, with a 100-nm-in-diameter antidot in the center. The presence of an antidot in the channel force electrons to split their paths, which then merge after the antidot. Such interference of their wave functions will change the normal transport behaviors of 1D electron gas. The two terminal magneto-conductance measurements taken at 0.3 K have shown intriguing yet different features under these two geometries. We observed inference patterns by controlling the gates separately, which can be suppressed after certain magnetic fields applied normal to the sample surface. Our devices also provide the opportunity to modulate electron modes from two paths and to study the tunable Aharonov-Bohm effect. In the current configuration we cannot detect the resonant tunneling of edge states via the embedded anitdot, which has been proposed for spin-filtering application. To further understand the physics behind the interference patterns, possibilities and limitation in device application, a refined measurement set-up at a lower temperature is needed.

並列關鍵字

Q1D ； QPC ； GaAs/AlGaAs ； antidot ； magneto-conductance ； Aharonov-Bohm effect (AB effect)

參考文獻

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Williamson, L. P. Kouwenhoven, D. van der Marel, and C. T.

Foxon, “Quantized conductance of point contacts in a two dimensional electron gas,” Phys. Rev. Lett., vol. 60, pp. 848–850, Feb 1988.

[4] P. F. Bagwell, “Evanescent modes and scattering in quasi-one dimensional wires,” Phys. Rev. B, vol. 41, pp. 10354–10371, May 1990.