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Orbital magnetization in semiconductors

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Chinese Physics B 2009年第12期18卷 5431-5436页

作者：方诚王志刚李树深张平 Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of Sciences Physics Department East China Institute of Technology Institute of Applied Physics and Computational Mathematics Institute of Applied Physics and Computational Mathematics Beijing 100088China Center for Applied Physics and Technology Peking University

This paper theoretically investigates the orbital magnetization of electron-doped （n-type） semiconductor het-erostructures and of hole-doped （p-type） bulk semiconductors, which are respectively described by a two-dimensional electron/hole Hamiltonian with both the included Rashba spin-orbit coupling and Zeeman splitting terms. It is the Zeeman splitting, rather than the Rashba spin-orbit coupling, that destroys the time-reversal symmetry of the semiconductor systems and results in nontrivial orbital magnetization. The results show that the magnitude of the orbital magnetization per hole and the Hall conductance in the p-type bulk semiconductors are about 10^-2-10^-1 effective Bohr magneton and 10^-1-1 e^2/h, respectively. However, the orbital magnetization per electron and the Hall conductance in the n-type semiconductor heterostructures are too small to be easily observed in experiment.

关键词： orbital magnetization Zeeman splitting Berry phase effect semiconductor

Quantum confinement effects and source-to-drain tunneling in ultra-scaled double-gate silicon n-MOSFETs

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Chinese Physics B 2012年第2期21卷 490-497页

作者：姜向伟李树深 State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesP.O.Box 912Beijing 100083China

By using the linear combination of bulk band （LCBB） method incorporated with the top of the barrier splitting （TBS） model, we present a comprehensive study on the quantum confinement effects and the source-to-drain tunneling in the ultra-scaled double-gate （DG） metal-oxide semiconductor field-effect transistors （MOSFETs）. A critical body thickness value of 5 nm is found, below which severe valley splittings among different X valleys for the occupied charge density and the current contributions occur in ultra-thin silicon body structures. It is also found that the tunneling current could be nearly 100% with an ultra-scaled channel length. Different from the previous simulation results, it is found that the source-to-drain tunneling could be effectively suppressed in the ultra-thin body thickness （2.0 nm and below） by the quantum confinement and the tunneling could be suppressed down to below 5% when the channel length approaches 16 nm regardless of the body thickness.

关键词： quantum confinement tunneling metal-oxide-semiconductor field-effect transistors linear combination of bulk band

Quantum Mechanical Study on Tunnelling and Ballistic Transport of Nanometer Si MOSFETs

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Chinese Physics Letters 2010年第5期27卷 196-199页

作者：邓惠雄姜向伟唐黎明 State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences PO Box 912 Beijing 100083 Department of Applied Physics Hunan University Changsha 410082

Using self-consistent calculations of million-atom SchrSdinger-Poisson equations, we investigate the I-V characteristics of tunnelling and ballistic transport of nanometer metal oxide semiconductor field effect transistors （MOSFET） based on a full 3-D quantum mechanical simulation under nonequilibtium condition. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. We find that the ballistic transport dominates the I-V characteristics, whereas the effects of tunnelling cannot be neglected with the maximal value up to 0.8mA/μm when the channel length of MOSFET scales down to 25 nm. The effects of tunnelling transport lower the threshold voltage Vt. The ballistic current based on fully 3-D quantum mechanical simulation is relatively large and has small on-off ratio compared with results derived from the calculation methods of Luo et al.

关键词： calculation ballistic transport characteristics

Orbital magnetization of the electron gas on a two-dimensional kagome' lattice under a perpendicular magnetic field

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Science China(Physics,Mechanics & Astronomy) 2012年第10期55卷 1791-1797页

作者： YUAN ZiGang WANG ZhiGang FU ZhenGuo LI ShuShen ZHANG Ping School of Science Belting University of Chemical TechnologyBeijing 100029China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP O.Box 8009Beijing 100088China State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesP.O.Box 912Beijing 100083China

The orbital magnetization of the electron gas on a two-dimensional kagome' lattice under a perpendicular magnetic field is theoretically *** interplay between the lattice geometry and magnetic field induces nontrivial k-space Chern invariant in the magnetic Brillouin zone,which turns to result in profound effects on the magnetization *** show that the Berry-phase term in the magnetization gives a paramagnetic contribution,while the conventional term brought about by the magnetic response of the magnetic Bloch bands produces a diamagnetic *** a result,the superposition of these two components gives rise to a delicate oscillatory structure in the magnetization curve when varying the electron filling *** relationship between this oscillatory behavior and the Hofstadter energy spectrum is revealed by selectively discussing the magnetization and its two components at the commensurate fluxes of f = 1/4,1/3,and 1/6,*** particular,we reveal as a typical example the fractal structure in the magnetic oscillations by tuning the commensurate flux around f = 1/*** finite-temperature effect on the magnetization is also discussed.

关键词：二维电子气磁化特性垂直磁场晶格轨道振荡行为 Berry 顺磁性

Quantum Measurement and Extended Feynman Path Integral

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Communications in Theoretical Physics 2012年第6期57卷 967-982页

作者：文伟白彦魁 Institute of Semiconductors Chinese Academy of Sciences College of Physical Science and Information Engineering Hebei Normal University

Quantum measurement problem has existed many years and inspired a large of literature in both physics and philosophy,but there is still no conclusion and consensus on *** show it can be subsumed into the quantum theory if we extend the Feynman path integral by considering the relativistic effect of Feynman *** to this extended theory,we deduce not only the Klein-Gordon equation,but also the wave-function-collapse *** is shown that the stochastic and instantaneous collapse of the quantum measurement is due to the "potential noise" of the apparatus or environment and "inner correlation" of wave function ***,the definite-status of the macroscopic matter is due to itself and this does not disobey the quantum *** work will give a new recognition for the measurement problem.

关键词： Feynman路径积分量子测量 Klein-Gordon方程费曼路径积分测量问题相对论效应量子理论量子力学

Maximal Heat Generation in Nanoscale Systems

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Chinese Physics Letters 2009年第3期26卷 234-235页

作者：周利玲李树深曾朝阳 State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 Department of Physics diangxi Normal University Nanchang 330022

We investigate the heat generation in a nanoscale system coupled to normal leads and find that it is maximal when the average occupation of the electrons in the nanoscale system is 0.5, no matter what mechanism induce... 详细信息

关键词： NANOELECTROMECHANICAL systems ELECTRIC machinery -- Thermodynamics TEMPERATURE measurements ELECTRONS MAXIMA & minima