D. C. Tsui

Princeton University, Princeton, New Jersey, United States

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Publications (580)1851.85 Total impact

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    ABSTRACT: We report spontaneous narrow band oscillations in the high field Wigner solid. These oscillations are similar to the recently seen and yet unexplained oscillations in the reentrant integer quantum Hall states. The current-voltage characteristic has a region of negative differential resistance in the current biased setup and it is hysteretic in the voltage biased setup. As a consequence of the unusual breakdown, the oscillations in the Wigner solid are of the relaxation type.
    Physical Review Letters 03/2007; 98(6):066805. · 7.73 Impact Factor
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    ABSTRACT: The results of experimental transport studies involving a series of thin GaAs/AlGaAs quantum wells with varying well widths will be reported. The mobility, mu, of thin GaAs/AlGaAs quantum wells is typically limited by electron scattering from the interfacial roughness of the quantum well. The total scattering rate due to all scattering mechanisms is determined from the mobility through &-1circ;=e/mum^* where m^* is the effective electron mass. Our series of samples consists of well widths of L=7.9, 9.9, 12.9, 16.0 and 33.0 nm. For constant electron density (ne˜5.5x10^10 cm-2) we find that interfacial roughness is the dominant scattering mechanism for L
    03/2007;
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    ABSTRACT: We have fabricated enhancement-mode p-channel GaAs MOSFETs on the (100) surface of undoped GaAs/AlxGa1-xAs heterostructures, using atomic-layer-deposited Al2O3 dielectric and Ti/Au gate, and measured their transport properties. The capacitively induced 2D hole density (p), determined from Shubnikov-de Haas oscillations, can be tuned from 9x10^9 to 3x10^11cm-2 by applying a negative gate bias. Within this range, the effective capacitance is close to that of an ideal parallel plate capacitor, and the leakage current remains virtually zero. The highest possible density is limited by the heterostructure design, not by gate leakage. The 2D hole mobility at T=0.3K increases with p and saturates at 6.3x10^5 cm^2/Vs for p>2.3x10^11cm-2. In this talk, we present data on transistor drain current-voltage characteristics, as well as magneto transport and the quantum Hall effects.
    03/2007;
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    ABSTRACT: We report measurements of the RF diagonal conductivity, Re[sigmaxx(f)], of ultrahigh mobility 2D electron systems with Landau level (LL) filling factor 4
    03/2007;
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    ABSTRACT: We present finite frequency conductivity measurements on ultra high mobility two-dimensional electron systems in GaAs/AlGaAs. At low temperature T
    03/2007;
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    ABSTRACT: We have studied the magneto-transport of two dimensional electron systems with various amount of short-range alloy disorder. Our samples are AlxGa1-xAs-Al0.32Ga0.68As heterostructures with the Al concentration x ranging from 0 to 0.85%, and the electron mobility varies from 1.2x10^7cm^2/V.s down to 8.9x10^5cm^2 /V.s within this x range. We have two major observations in the high magnetic field regime. First, we have found that the amplitude of the fractional quantum Hall gaps is independent on x. Second, and more surprisingly, we have observed a nu=1 reentrant integer quantum Hall effect (RIQHE) between the Landau level filling factor nu=2/3 and nu=3/5 in the sample with x=0.85%. Between the quantum Hall Plateaus of nu=2/3 and nu=3/5, the Hall resistance is observed to be quantized to h/e^2 while the longitudinal resistance reaches a deep minimum.
    03/2007;
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    ABSTRACT: In a high mobility two-dimensional electron system in Si, near the critical density, $n_c=0.32\times10^{11}$cm$^{-2}$, of the apparent metal-to-insulator transition, the conductivity displays a linear temperature ($T$) dependence around the Fermi temperature. When $\sigma_0$, the extrapolated T=0 conductivity from the linear T-dependence, is plotted as a function of density, two regimes with different $\sigma_0(n)$ relations are seen, suggestive of two different phases. Interestingly, a sharp transition between these two regimes coincides with $n_c$, and $\sigma_0$ of the transition is $\sim$ $e^2/h$, the quantum conductance, per square. Toward T=0, the data deviate from linear $\sigma(T)$ relation and we discuss the possible percolation type of transition in our Si sample.
    Physical Review B 01/2007; 75(3):033314. · 3.66 Impact Factor
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    ABSTRACT: The authors demonstrate that a high mobility two-dimensional electron gas can be capacitively induced in an undoped Si/Si1-xGex heterostructure using atomic-layer-deposited Al2O3 as the dielectric. The density is tuned up to 4.2×1011/cm2, limited by the gate leakage current. The mobility increases with the density rapidly and reaches 5.5×104 cm2/V s at the highest density. The observation of well developed quantum Hall states and two-dimensional metal-insulator transition shows that the devices are suitable for two-dimensional electron physics studies.
    Applied Physics Letters 01/2007; 90. · 3.79 Impact Factor
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    ABSTRACT: We have fabricated undoped p-channel GaAs/AlxGa1−xAs heterostructure field-effect transistors with nearly ideal drain current-voltage characteristics, using atomic-layer-deposited Al2O3 as the dielectric, and measured their transport properties. At 0.3K, the densities and mobilities of the two dimensional holes can be tuned up to 2.9×10 11 /cm 2 and 6.4×10 5 cm 2 /Vs respectively. The variable density high mobility two-dimensional hole system provides a large parameter space for the study of two-dimensional physics. Appl. Phys. Lett. 90, 112113 (2007) High mobility two-dimensional electron gases (2DEGs) have benefited research in condensed matter physics and brought about many interesting physical phenomena [1]. Conventionally there are two ways of realizing 2DEGs. Modulation-doping is the most widely used technique for GaAs/Al x Ga 1−x As heterostructures, in which electrons transfer from dopants in the barrier layer to the het-erojunction interface and form the high mobility 2DEG. Metal-oxide-semiconductor field-effect transistors (MOS-FETs) are quite popular for Si-based systems, utilizing a high quality thermal oxide not available in other semi-conductors. In a MOSFET, the 2DEG is induced at the interface of the semiconductor and the amorphous oxide by an electric field. The nature of disorder in the two types of 2DEGs is significantly different and is expected to have impact on their physical properties. Fabrication of enhancement-mode (e-mode) GaAs transistors has proved to be a difficult task, primarily due to the lack of a good thermal oxide on GaAs surfaces [2]. The heterostructure-insulated-gate field effect transistor (HIGFET), whose insulating layer is molecular beam epi-taxy (MBE) grown Al x Ga 1−x As, is so far the only widely studied GaAs-based e-mode device [3, 4]. Different varia-tions of the HIGFET have also been demonstrated [5–8]. However, the insulating layer has an intrinsically small barrier height. Significant leakage current flows at large gate voltages and limits the tunable density range of the 2D carriers.
    Applied Physics Letters 01/2007; 90. · 3.79 Impact Factor
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    ABSTRACT: Wigner solids in two-dimensional electron systems in high magnetic field B exhibit a striking, microwave or rf resonance, that is understood as a pinning mode. The temperature, Tm, above which the resonance is absent, is interpreted as the melting temperature of the solid. Studies of Tm for many B and many sample densities n show that Tm is a function of the Landau level filling ν alone for a given sample. This indicates that quantum mechanics figures importantly in the melting. Tm also appears to be increased by larger sample disorder.
    International Journal of Modern Physics B 01/2007; 21(08-09). · 0.46 Impact Factor
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    ABSTRACT: We present a fabrication process and results of transport measurements of a number of p-channel heterojunction-insulated-gate field-effect transistors (HIGFETs). Without intentional doping in HIGFETs, the disorder is likely to be less than that in the modulation-doped samples. We established a process that eliminates the well-known gate leakage problem. The hole density in our devices can be continuously tuned down to a record low value of 7 × 108 cm-2. Remarkably, such a dilute system (with Fermi wavelength approaching 1 mum) exhibits a non-activated conductivity that grows with temperature approximately as a power law at sufficiently low temperatures. We contrast it with the activated transport found in more disordered samples and discuss possible transport mechanisms in this strongly-interacting regime.
    International Journal of Modern Physics B 01/2007; 21:1219-1227. · 0.46 Impact Factor
  • D.C. Tsui
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    ABSTRACT: An overview is given of some recent experiments on the localization-delocalization transition in the integral quantum Hall effect and the new quantum liquid ground states giving rise to the fractional quantum Hall effect.
    Annals of the New York Academy of Sciences 12/2006; 581(1):160 - 168. · 4.38 Impact Factor
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    ABSTRACT: Cyclotron resonance at microwave frequencies is used to measure the band mass (mb) of the two-dimensional holes (2DHs) in carbon-doped (100) GaAs/ AlxGa1−xAs heterostructures. The measured mb shows strong dependences on both the 2DH density (p) and the GaAs quantum well width (W). For a fixed W, in the density range (0.4×1011 to 1.1×1011 cm−2) studied here, mb increases with p, consistently with previous studies of the 2DHs on the (311)A surface. For a fixed , mb increases from 0.22me at to 0.50me at , and saturates around 0.51me for .
    Solid State Communications 12/2006; · 1.53 Impact Factor
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    ABSTRACT: A SiGe quantum dot single-hole transistor passivated by silicon epitaxial regrowth with extremely stable Coulomb blockade oscillations has been demonstrated. The quantum dot was defined by atomic force microscopy nanopatterning technique and subsequently passivated by the epitaxial regrowth of silicon. Such passivation of the dot avoids any potential defect states on the dot associated with the Si / Si O <sub>2</sub> interface. Coulomb blockade oscillations controlled by side planar gating at ∼0.3 K are reproducible, in sharp contrast with the noisy and irreproducible I-V characteristics of unpassivated SiGe quantum dot devices. An additional top gate was used to further tune the Coulomb blockade oscillations, enabling a shift in side-gate voltage of up to three periods.
    Journal of Applied Physics 12/2006; · 2.21 Impact Factor
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    ABSTRACT: Recent experiments have shown that two-dimensional electron systems with an externally applied magnetic field are an extremely rich ground for many-body physics. In particular, when only two of the Landau levels (LL) are filled an intricate magnetoresistance is found. This result stems from an interesting competition of electronic phases such as fractional quantum Hall liquids, reentrant integer Hall states, and unique quantized states at even denominator LL filling factors. We present a brief review of the transport properties of these electronic phases and discuss in detail the effects of an added in-plane magnetic field. (c) 2006 Elsevier B.V. All rights reserved.
    Physica E Low-dimensional Systems and Nanostructures 12/2006; · 1.86 Impact Factor
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    ABSTRACT: The power-law increase of the conductivity with temperature in the nominally insulating regime, recently reported for the dilute two-dimensional holes [cond-mat/0603053], is found to systematically vary with the carrier density. Based on the results from four different GaAs heterojunction-insulated-gate field-effect-transistor samples, it is shown that the power law exponent depends on a single dimensionless parameter, the ratio between the mean carrier separation and the distance to the metallic gate that screens the Coulomb interaction. This dependence suggests that the carriers form a correlated state in which the interaction effects play a significant role in the transport properties.
    11/2006;
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    ABSTRACT: We report the observation of the apparent metal-insulator transition (MIT) of two-dimensional electrons in a high quality modulation doped Si/Si1-xGex heterostructure. The critical density nc, at which the thermal coefficient of its low temperature resistivity changes sign, is 0.32×1011 cm-2, much smaller than the nc of ~ 0.8×1011cm-2 seen in clean Si-MOSFET's. This is consistent with previous observations in 2D holes in GaAs that nc decreases with decreasing disorder.
    09/2006;
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    ABSTRACT: The authors design and demonstrate an InGaAs/InGaAsP quantum well infrared photodetector for high-speed infrared detection. The InGaAsP is selected as the barrier material to provide a large photoconductive gain, and the well is made of InGaAs/InP superlattice to achieve a broadband absorption. These features are expected to increase the photocurrent of the detector under a broadband source. For quantitative comparison, we also fabricate a quantum well GaAs/AlGaAs superlattice detector with a similar spectrum. Dark current noise measurement indicates that the gain of the InGaAs/InGaAsP detector is 4.6 times larger than that of the reference detector, thus confirming the present design concept.
    Applied Physics Letters 08/2006; 89(8):081128-081128-3. · 3.79 Impact Factor
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    ABSTRACT: The melting temperature ($T_m$) of a solid is generally determined by the pressure applied to it, or indirectly by its density ($n$) through the equation of state. This remains true even for helium solids\cite{wilk:67}, where quantum effects often lead to unusual properties\cite{ekim:04}. In this letter we present experimental evidence to show that for a two dimensional (2D) solid formed by electrons in a semiconductor sample under a strong perpendicular magnetic field\cite{shay:97} ($B$), the $T_m$ is not controlled by $n$, but effectively by the \textit{quantum correlation} between the electrons through the Landau level filling factor $\nu$=$nh/eB$. Such melting behavior, different from that of all other known solids (including a classical 2D electron solid at zero magnetic field\cite{grim:79}), attests to the quantum nature of the magnetic field induced electron solid. Moreover, we found the $T_m$ to increase with the strength of the sample-dependent disorder that pins the electron solid.
    Nature Physics 05/2006; · 19.35 Impact Factor
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    ABSTRACT: In a high quality two-dimensional electron system of density n ˜1x10^11 cm-2 and mobility mu˜10 x10^6 cm^2/Vs, at the temperature (T) of 1.2K, the diagonal magnetoresistance, Rxx, shows a strictly linear magnetic (B) field dependence, except for sharp spikes at B- fields where the integer quantum Hall effect develops. As T is lowered to ˜ 35 mK, the main feature of Rxx is now dominated by multiple minima and peaks, due to the formation of integer and fractional quantum Hall states. However, when plotting Rxx at the even-denominator fillings (nu=1/4, 1/2, 3/4, and 3/2) as a function of B field, the same linear B field dependence is recovered. Interestingly, this linear magnetoresistance cannot be understood under the composite fermion model. Rather, it can be explained in terms of a slight, unintentional electron density gradient in our sample: Practically all Rxx features can be reproduced quantitatively through Rxy. We will discuss the implications of this finding.
    03/2006;

Publication Stats

13k Citations
1,851.85 Total Impact Points

Institutions

  • 1983–2014
    • Princeton University
      • • Department of Electrical Engineering
      • • Department of Physics
      Princeton, New Jersey, United States
  • 2004–2012
    • Sandia National Laboratories
      • Semiconductor Material and Device Sciences Department
      Albuquerque, New Mexico, United States
    • University of Florida
      • Department of Physics
      Gainesville, Florida, United States
  • 2002–2010
    • National High Magnetic Field Laboratory
      Tallahassee, Florida, United States
  • 2008
    • Purdue University
      • Department of Physics
      West Lafayette, IN, United States
  • 2005
    • NASA
      Washington, West Virginia, United States
  • 1998–2005
    • Columbia University
      • Department of Physics
      New York City, NY, United States
    • AT&T Labs
      Austin, Texas, United States
  • 2002–2004
    • Florida State University
      • Department of Physics
      Tallahassee, Florida, United States
  • 2001
    • JDS Uniphase Corporation
      Milpitas, California, United States
  • 1995–1996
    • The University of Tokyo
      • Institute of Industrial Science
      Tokyo, Tokyo-to, Japan
  • 1989–1990
    • Massachusetts Institute of Technology
      • Department of Electrical Engineering and Computer Science
      Cambridge, Massachusetts, United States
  • 1984
    • Harvard University
      Cambridge, Massachusetts, United States
  • 1982–1983
    • Max Planck Institute for Solid State Research
      Stuttgart, Baden-Württemberg, Germany