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对磁量子结构中电子在外加恒定电场下的输运性质进行了研究.分别计算了电子隧穿相同磁垒磁阱和不同磁垒磁阱构成的两种磁量子结构的传输概率和电流密度.计算结果表明,在相当宽广的非共振电子入射能区,外加电场下电子的传输概率比无电场时增加.对于电子隧穿相同磁垒磁阱构成的双磁垒结构,共振减弱;对于电子隧穿不同磁垒磁阱构成的双磁垒结构,无电场作用时的非完全共振在适当的偏置电压下转化为完全共振,这时的电子可实现理想的共振隧穿.研究同时表明,磁量子结构中存在着显著的量子尺寸效应和负微分电导. 相似文献
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磁性隧道结材料中自旋相关的量子阱态所导致的共振隧穿现象具有很重要的研究和应用价值,文章介绍了最近在Fe(001)/MgO/Fe/MgO/Fe双势垒磁性隧道结中存在的量子阱共振隧穿效应的理论研究工作,通过量子阱态的第一性原理的计算以及结合对中间Fe薄膜孤岛结构所导致Coulomb阻塞效应的分析,证实了最近Nozaki等人(Nozaki T et al.Phys.Rev.Lett.,2006,96:027208)实验中得到的振荡效应确实来源于中间Fe层多数自旋电子在Г点处形成的△1对称性的量子阱态.Coulomb阻塞效应的存在正是导致实验中低温下量子阱共振隧穿效应不够明显的主要原因. 相似文献
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采用分子束外延技术生长GaAs/AlAs三量子阱,并在中间的GaAs阱中δ-掺杂浅受主杂质Be原子,制作出量子限制受主远红外Teraherz原型电致发光器件.实验上测量得到4.5 K时器件的电致发光谱(EL)和电传输特性(I-V曲线).在EL发射谱中清楚地观察到222 cm-1处宽的尖峰,这来源于Be受主奇宇称激发态到其基态的辐射跃迁,而非辐射弛豫过程则使发射谱的信号很弱.另外在I-V曲线中072和186 V的位置出现两个共振隧道贯穿现象,分别对应于中间δ-掺杂量子阱受主能级1s3/2(Γ6+Γ7)到左边非掺GaAs量子阱中HH带,及右边非掺杂GaAs量子阱中HH重空穴带到中间掺杂GaAs量子阱中Be受主杂质原子奇宇称激发态2p5/2(Γ6+Γ7)能级的共振隧穿.
关键词:
量子限制效应
电致发光
共振隧穿效应
δ-掺杂GaAs/AlAs三量子阱 相似文献
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非铁磁金属层中的量子阱态在磁输运过程中的重要性已被广泛认识.铁磁金属层中自旋极化的量子阱态以前并没有详尽的理论研究;实验上也没有清晰地观测到自旋极化量子阱态的隧穿.文章介绍了最近由卢仲毅、张晓光和Pantelides预言的Fe/MgO/FeO/Fe/Cr和其他铁磁量子阱隧道结中的共振隧穿,并解释铁、钴、铬的△1能带的对称性在这种共振隧穿中的作用. 相似文献
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基于Ξ形四能级模型运用密度矩阵方程研究了非对称量子阱中非定域激子复合发光特性.理论结果表明:非定域激子复合发光具有双峰特征,两峰相对于中心跃迁频率的红移和蓝移量与电子和空穴的振荡频率密切相关.与单量子阱相比,这种频率移动对外加电场相当敏感,即当外加反向电场作小的变化时,两峰有较大的移动,表现强量子限域斯塔克效应.这意味着利用非对称量子阱在新一代高速调制器和光开关中具有潜在的应用价值.
关键词:
非对称耦合量子阱
共振隧穿
非定域激子
量子限域斯塔克效应 相似文献
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硅—二氧化硅超晶格:探索硅基发光材料的一条新途径 总被引:4,自引:0,他引:4
理论上认为,由于Si/SiO2超晶格中硅层(阱层)的电子和空穴都受到极强的量子限制效应,硅层能带有可能从体硅的间接带隙转变为直接带隙,从而发光效率大大提高.实验上,在非晶Si/SiO2超晶格中观察到在可见光波段的室温光致发光和明显的量子限制效应现象.晶体Si/SiO2超晶格研究也取得了初步的结果. 相似文献
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研究了零偏压和偏置电压作用下磁量子结构中自旋电子的隧穿输运性质. 结果表明电子自旋 输运的性质不仅取决于磁量子结构的构型、入射电子的能量和波矢, 而且取决于偏置电压. 在零偏压下, 由等同的磁垒磁阱构成的磁量子结构不具有自旋过滤的特点, 而由不等同的磁 垒磁阱构成的磁量子结构却具有较好的自旋过滤特点. 偏置电压极大地改变了磁量子结构中 电子的极化程度, 使得电子隧穿等同的磁垒磁阱构成的磁量子结构的输运性质也显著地依赖 于电子的自旋指向.
关键词:
磁量子结构
自旋电子
隧穿输运
自旋极化 相似文献
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Electron transport properties of a triple-terminal Aharonov-Bohm interferometer are theoretically studied. By applying a Rashba spin-orbit coupling to a quantum dot locally, we find that remarkable spin polarization comes about in the electron transport process with tuning the structure parameters, i.e., the magnetic flux or quantum dot levels. When the quantum dot levels are aligned with the Fermi level, there only appear spin polarization in this structure by the presence of an appropriate magnetic flux. However,in absence of magnetic flux spin polarization and spin separation can be simultaneously realized with the adjustment of quantum dot levels, namely, an incident electron from one terminal can select a specific terminal to depart from the quantum dots according to its spin state. 相似文献
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The electron transport in a semiconducting armchair graphene nanoribbon with line defect is theoretically investigated, by coupling it to two normal metallic leads. It is found that the line defect induces a new localized quantum state near the Dirac point, and that the coupling between this state and the leads provides a channel for the resonant tunneling. This means that such a finite‐size nanoribbon can be viewed as a quantum dot. When two line defects are present simultaneously, a coupled quantum dot forms, leading to the splitting of the conductance peaks. With these results, we propose such a structure to be a promising candidate of an electron transistor. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Eickemeyer F Reimann K Woerner M Elsaesser T Barbieri S Sirtori C Strasser G Müller T Bratschitsch R Unterrainer K 《Physical review letters》2002,89(4):047402
Coherent electron transport is studied in an electrically driven quantum cascade structure. Ultrafast quantum transport from the injector into the upper laser state is investigated by midinfrared pump-probe experiments directly monitoring the femtosecond saturation and subsequent recovery of electrically induced optical gain. We demonstrate for the first time pronounced gain oscillations giving evidence for a coherent electron motion. The coexistence of a long dephasing time of quantum coherence and high Coulomb scattering rates in the injector points to the occurrence of scattering-induced coherence in electron transport. 相似文献
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Wei-Ping Li Ji-Wen Yin Yi-Fu Yu Jing-Lin Xiao Zi-Wu Wang 《International Journal of Theoretical Physics》2009,48(12):3339-3344
The time evolution of the quantum mechanical state of an electron is calculated by using variational method of Pekar type
on the condition of electric-LO phonon strong coupling in a parabolic quantum dot. We obtained the eigen energies of the ground
state and the first-excited state, the eigen functions of the ground state and the first-excited state this system in a quantum
dot may be employed as a two-level quantum system-qubit. The supposition electron is in system’s ground state in the initial
time, the electron transit from the ground state to the excited state in presence of an electric field F along the x axis. The results indicate that the electron transition probability and the oscillation period increase with decreasing the
electron-LO-phonon coupling constant, increasing the electric field and the confinement length. 相似文献
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《Physics letters. A》2019,383(25):3143-3148
A number of experiments in superfluid helium-4 over the past fifty years on the mobility of electron bubbles, which are unique quantum dots in the liquid state, revealed the existence of a “fast” ion and other “exotic” negative ions whose origin and structure still remains unresolved. The fast ion has a mobility which is six times that of the well understood single electron bubble and the other ions span a region from the fast ion mobility to that of the electron bubble. The work presented here shows that a net anionic, two electron, core-shell quantum dot could potentially explain these findings and provide direction for new experimental work. The model described is based on the quantum confinement and stabilization of short-lived shape resonances which originate from anti-bonding orbitals. 相似文献
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D. S. Abramkin K. M. Rumynin A. K. Bakarov D. A. Kolotovkina A. K. Gutakovskii T. S. Shamirzaev 《JETP Letters》2016,103(11):692-698
The crystal structure of new self-assembled InSb/AlAs and AlSb/AlAs quantum dots grown by molecularbeam epitaxy has been investigated by transmission electron microscopy. The theoretical calculations of the energy spectrum of the quantum dots have been supplemented by the experimental data on the steady-state and time-resolved photoluminescence spectroscopy. Deposition of 1.5 ML of InSb or AlSb on the AlAs surface carried out in the regime of atomic-layer epitaxy leads to the formation of pseudomorphically strained quantum dots composed of InAlSbAs and AlSbAs alloys, respectively. The quantum dots can have the type-I and type-II energy spectra depending on the composition of the alloy. The ground hole state in the quantum dot belongs to the heavy-hole band and the localization energy of holes is much higher than that of electrons. The ground electron state in the type-I quantum dots belongs to the indirect XXY valley of the conduction band of the alloy. The ground electron state in the type-II quantum dots belongs to the indirect X valley of the conduction band of the AlAs matrix. 相似文献