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1.
Nanotechnology ; 22(44): 445701, 2011 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-21975543

RESUMO

One-dimensional superconducting transistors have been fabricated with individual InAs nanowires (NWs) using radio-frequency sputter cleaning followed by in situ metal deposition. Because of the highly transparent contacts formed in between the InAs NWs and the metals, supercurrent, multiple Andreev reflections and Shapiro steps under microwave radiation have been observed. Near pinch-off gate regions, Fabry-Perot interference and a normal conductance quantization with resonant features have been observed, which were found to be correlated with a supercurrent flow.

2.
Nano Lett ; 9(9): 3151-6, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19736971

RESUMO

We report on magnetotransport measurements on InSb nanowire quantum dots. The measurements show that the quantum levels of the InSb quantum dots have giant g factors, with absolute values up to approximately 70, the largest value ever reported for semiconductor quantum dots. We also observe that the values of these g factors are quantum level dependent and can differ strongly between different quantum levels. The presence of giant g factors indicates that considerable contributions from the orbital motion of electrons are preserved in the measured InSb nanowire quantum dots, while the level-to-level fluctuations arise from spin-orbit interaction. We have deduced a value of Delta(SO) = 280 mueV for the strength of spin-orbit interaction from an avoided level crossing between the ground state and first excited state of an InSb nanowire quantum dot with a fixed number of electrons.


Assuntos
Antimônio/química , Índio/química , Nanofios/química , Pontos Quânticos , Elétrons , Teste de Materiais , Nanotecnologia , Tamanho da Partícula , Teoria Quântica , Semicondutores , Silício/química , Propriedades de Superfície
3.
Nano Lett ; 9(2): 779-83, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19159269

RESUMO

When a quantum dot is subjected to a thermal gradient, the temperature of electrons entering the dot can be determined from the dot's thermocurrent if the conductance spectrum and background temperature are known. We demonstrate this technique by measuring the temperature difference across a 15 nm quantum dot embedded in a nanowire. This technique can be used when the dot's energy states are separated by many kT and will enable future quantitative investigations of electron-phonon interaction, nonlinear thermoelectric effects, and the efficiency of thermoelectric energy conversion in quantum dots.

5.
Nano Lett ; 8(3): 872-5, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18302328

RESUMO

We demonstrate radio frequency single-electron transistors fabricated from epitaxially grown InAs/InP heterostructure nanowires. Two sets of double-barrier wires with different barrier thicknesses were grown. The wires were suspended 15 nm above a metal gate electrode. Electrical measurements on a high-resistance nanowire showed regularly spaced Coulomb oscillations at a gate voltage from -0.5 to at least 1.8 V. The charge sensitivity was measured to 32 microe rms Hz(-1/2) at 1.5 K. A low-resistance single-electron transistor showed regularly spaced oscillations only in a small gate-voltage region just before carrier depletion. This device had a charge sensitivity of 2.5 microe rms Hz(-1/2). At low frequencies this device showed a typical 1/f noise behavior, with a level extrapolated to 300 microe rms Hz(-1/2) at 10 Hz.

6.
Nano Lett ; 5(4): 635-8, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15826100

RESUMO

We demonstrate storage of electrons in semiconductor nanowires epitaxially grown from Au nanoparticles. The nanowires contain multiple tunnel junctions (MTJs) of InP barriers and InAs quantum dots designed such that the metal seed particles act as storage nodes. By positioning a second nanowire close to the seed particle it is possible to detect tunneling of individual electrons through the MTJ at 4.2 K. A strong memory effect is observed in the detector current when sweeping the writing voltage.

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