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Cyclotron-resonance-assisted photon drag effect in InSb/InAlSb quantum wells excited by terahertz radiation  [PDF]
S. Stachel,G. V. Budkin,U. Hagner,V. V. Bel'kov,M. M. Glazov,S. A. Tarasenko,S. K. Clowes,T. Ashley,A. M. Gilbertson,S. D. Ganichev
Physics , 2013, DOI: 10.1103/PhysRevB.89.115435
Abstract: We report on the observation of the cyclotron-resonance-assisted photon drag effect. Resonant photocurrent is detected in InSb/InAlSb quantum wells structures subjected to a static magnetic field and excited by terahertz radiation at oblique incidence. The developed theory based on Boltzmann's kinetic equation is in a good agreement with the experimental findings. We show that the resonant photocurrent originates from the transfer of photon momentum to free electrons drastically enhanced at cyclotron resonance.
Gate-tunable high mobility remote-doped InSb/In_{1-x}Al_{x}Sb quantum well heterostructures  [PDF]
Wei Yi,Andrey A. Kiselev,Jacob Thorp,Ramsey Noah,Binh-Minh Nguyen,Steven Bui,Rajesh D. Rajavel,Tahir Hussain,Mark Gyure,Philip Kratz,Qi Qian,Michael J. Manfra,Vlad S. Pribiag,Leo P. Kouwenhoven,Charles M. Marcus,Marko Sokolich
Physics , 2015, DOI: 10.1063/1.4917027
Abstract: Gate-tunable high-mobility InSb/In_{1-x}Al_{x}Sb quantum wells (QWs) grown on GaAs substrates are reported. The QW two-dimensional electron gas (2DEG) channel mobility in excess of 200,000 cm^{2}/Vs is measured at T=1.8K. In asymmetrically remote-doped samples with an HfO_{2} gate dielectric formed by atomic layer deposition, parallel conduction is eliminated and complete 2DEG channel depletion is reached with minimal hysteresis in gate bias response of the 2DEG electron density. The integer quantum Hall effect with Landau level filling factor down to 1 is observed. A high-transparency non-alloyed Ohmic contact to the 2DEG with contact resistance below 1{\Omega} \cdot mm is achieved at 1.8K.
Magneto-transport study of top- and back-gated LaAlO$_3$/SrTiO$_3$ heterostructures  [PDF]
W. Liu,S. Gariglio,A. F,D. Li,M. Boselli,D. Stornaiuolo,J. -M. Triscone
Physics , 2015, DOI: 10.1063/1.4921068
Abstract: We report a detailed analysis of magneto-transport properties of top- and back-gated LaAlO$_3$/SrTiO$_3$ heterostructures. Efficient modulation in magneto-resistance, carrier density, and mobility of the two-dimensional electron liquid present at the interface is achieved by sweeping top and back gate voltages. Analyzing those changes with respect to the carrier density tuning, we observe that the back gate strongly modifies the electron mobility while the top gate mainly varies the carrier density. The evolution of the spin-orbit interaction is also followed as a function of top and back gating.
A Surface-Gated InSb Quantum Well Single Electron Transistor  [PDF]
J. M. S. Orr,P. D. Buckle,M. Fearn,C. J. Storey,L. Buckle,T. Ashley
Physics , 2007, DOI: 10.1088/1367-2630/9/8/261
Abstract: Single electron charging effects in a surface-gated InSb/AlInSb QW structure are reported. This material, due to its large g-factor and light effective mass, offers considerable advantages over more commonly used materials, such as GaAs, for quantum information processing devices. However, differences in material and device technology result in significant processing challenges. Simple Coulomb blockade and quantised confinement models are considered to explain the observation of conductance oscillations in these structures. The charging energy is found to be comparable with the energy spectrum for single particle states.
Capacitance of Gated GaAs/AlGaAs Heterostructures Subject to In-plane Magnetic Fields  [PDF]
T. Jungwirth,L. Smrcka
Physics , 1995, DOI: 10.1103/PhysRevB.51.10181
Abstract: A detailed analysis of the capacitance of gated GaAs/AlGaAs heterostructures is presented. The nonlinear dependence of the capacitance on the gate voltage and in-plane magnetic field is discussed together with the capacitance quantum steps connected with a population of higher 2D gas subbands. The results of full self-consistent numerical calculations are compared to recent experimental data.
Electro-Mechanical Response of Top-Gated LaAlO3/SrTiO3 Heterostructures  [PDF]
Feng Bi,Mengchen Huang,Chung Wung Bark,Sangwoo Ryu,Sanghan Lee,Chang-Beom Eom,Patrick Irvin,Jeremy Levy
Physics , 2013,
Abstract: LaAlO3/SrTiO3 heterostructures are known to exhibit a sharp, hysteretic metal-insulator transition (MIT) with large enhanced capacitance near depletion. To understand the physical origin of this behavior, the electromechanical response of top-gated LaAlO3/SrTiO3 heterostructures is probed using two simultaneous measurement techniques: piezoforce microscopy (PFM) and capacitance spectroscopy. PFM measurements reveal local variations in the hysteretic response, which is directly correlated with capacitance measurements. The enhanced capacitance at the MIT is linked to charging/discharging dynamics of nanoscale conducting islands, which are revealed through PFM imaging and time-resolved capacitance and piezoresponse measurements.
Non-volatile gated variable resistor based on doped La_{2}CuO_{4} and SrTiO_{3} heterostructures  [PDF]
Dieter Weber,Ulrich Poppe
Physics , 2012, DOI: 10.1063/1.3691599
Abstract: Gated variable resistors were manufactured by depositing epitaxial heterostructures of doped La_{2}CuO_{4} and SrTiO_{3} layers. Their conductance change as function of write current I and write time t followed a simple empirical law of the form {\Delta}G/G = CI^A t^B. This behavior is in agreement with ionic transport that accelerates exponentially with electrical field strength.
Single-Crystal Organic Charge-Transfer Interfaces probed using Schottky-Gated Heterostructures  [PDF]
Ignacio Gutiérrez Lezama,Masaki Nakano,Nikolas A. Minder,Zhihua Chen,Flavia V. Di Girolamo,Antonio Facchetti,Alberto F. Morpurgo,.
Physics , 2013, DOI: 10.1038/nmat3383
Abstract: Organic semiconductors based on small conjugated molecules generally behave as insulators when undoped, but the hetero-interfaces of two such materials can show electrical conductivity as large as in a metal. Although charge transfer is commonly invoked to explain the phenomenon, the details of the process and the nature of the interfacial charge carriers remain largely unexplored. Here we use Schottky-gated heterostructures to probe the conducting layer at the interface between rubrene and PDIF-CN2 single crystals. Gate-modulated conductivity measurements demonstrate that interfacial transport is due to electrons, whose mobility exhibits band-like behavior from room temperature to ~ 150 K, and remains as high as ~ 1 cm2V-1s-1 at 30 K for the best devices. The electron density decreases linearly with decreasing temperature, an observation that can be explained quantitatively based on the heterostructure band diagram. These results elucidate the electronic structure of rubrene-PDIF-CN2 interfaces and show the potential of Schottky-gated organic heterostructures for the investigation of transport in molecular semiconductors.
Towards high mobility InSb nanowire devices  [PDF]
?nder Gül,David J. van Woerkom,Ilse van Weperen,Diana Car,Sébastien R. Plissard,Erik P. A. M. Bakkers,Leo P. Kouwenhoven
Physics , 2014, DOI: 10.1088/0957-4484/26/21/215202
Abstract: We study the low-temperature electron mobility of InSb nanowires. We extract the mobility at 4.2 Kelvin by means of field effect transport measurements using a model consisting of a nanowire-transistor with contact resistances. This model enables an accurate extraction of device parameters, thereby allowing for a systematic study of the nanowire mobility. We identify factors affecting the mobility, and after optimization obtain a field effect mobility of $\sim2.5\mathbin{\times}10^4$ cm$^2$/Vs. We further demonstrate the reproducibility of these mobility values which are among the highest reported for nanowires. Our investigations indicate that the mobility is currently limited by adsorption of molecules to the nanowire surface and/or the substrate.
Transistor operation and mobility enhancement in top-gated LaAlO_3 / SrTiO_3 heterostructures  [PDF]
M. Hosoda,Y. Hikita,H. Y. Hwang,C. Bell
Physics , 2013, DOI: 10.1063/1.4820449
Abstract: We report the operation of LaAlO_3 / SrTiO_3 depletion mode top-gated junction field-effect transistors using a range of LaAlO_3 thicknesses as the top gate insulator. Gated Hall bars show near ideal transistor characteristics at room temperature with on-off ratios greater than 1000. Lower temperature measurements demonstrate a systematic increase in the Hall mobility as the sheet carrier density in the channel is depleted via the top gate, providing a route to higher mobility, lower density electron gases in this system.
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