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Zhu J.,Universities of Inner Mongolia Autonomous Region | Ban S.L.,Universities of Inner Mongolia Autonomous Region | Ha S.H.,Inner Mongolia University of Technology
Modern Physics Letters B | Year: 2012

The ground state binding energies of donor impurities in strained [0001]-oriented wurtzite GaN/Al xGa 1-xN asymmetric double quantum wells are investigated using a variational method combined with numerical computation. The built-in electric field due to the spontaneous and strain-induced piezoelectric polarization and the strain modification on material parameters are taken into account. The variations of binding energies versus the width of central barrier, the ratio of two well widths, and the impurity position are presented, respectively. It is found that the built-in electric field causes a mutation of binding energies with increasing the width of central barrier to some value. The results for symmetrical double quantum wells and without the built-in electric field are also discussed for comparison. © World Scientific Publishing Company. Source

Xu B.,Universities of Inner Mongolia Autonomous Region | Wu H.-Y.,Universities of Inner Mongolia Autonomous Region | Zhang Y.-C.,CAS Institute of Physics | Wang H.-T.,CAS Institute of Physics | Liu W.-M.,CAS Institute of Physics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

A generalized double-well-basis coupled representation is proposed to investigate excitation spectra and thermodynamics of bosonic atoms in double-well optical superlattices. In the hard-core limit and with a filling factor of one, excitations describing the creation of pairs of a doubly occupied state and a simultaneous empty state, and those from a symmetric singly occupied state to an antisymmetric state are carefully analyzed and their excitation spectra are calculated within mean-field theory. Based on the hard-core statistics, the equilibrium properties such as heat capacity and particle populations are studied in detail. The cases with other filling factors are also briefly discussed. © 2015 American Physical Society. Source

Qu Y.,Inner Mongolia University of Technology | Qu Y.,Universities of Inner Mongolia Autonomous Region | Ban S.L.,Inner Mongolia University of Technology | Ban S.L.,Universities of Inner Mongolia Autonomous Region
Journal of Applied Physics | Year: 2011

Based on the dielectric continuum phonon model, uniaxial model and force balance equation, the influence of an InxGa1-xN nanogroove inserted in a strained wurtzite AlN/GaN/AlN quantum well on electron mobility is studied. The results show that the optical phonon modes will be changed by the introduction of InGaN/GaN interfaces and the In component. It can be also found that the electron wave function will shift to the InGaN layer as long as the conductor band energy at GaN/InGaN interface gets lower than that at the AlN/GaN interface. Electron mobility first increases and then decreases as x increases, whereas the mobility is always greater than the case without an InGaN nanogroove when electrons mainly distribute in the GaN layer. Once most of the electrons transfers to the InGaN nanogroove, electron mobility drops sharply and then increases with the increase of x. © 2011 American Institute of Physics. Source

Ren B.,Shanghai University | Cao M.,Shanghai University | Zhang Q.,Shanghai University | Huang J.,Shanghai University | And 5 more authors.
Journal of Alloys and Compounds | Year: 2016

CdS nanowires with controllable size, orientation, and morphology were synthesized on a large scale by a solvothermal method. The mechanism for the formation of CdS nanowires evolved from CdS spherical particles can be divided into a short-period solid-solid transformation process and a long-period ripening process. Near-band-emission without distinct split phenomenon was observed in the PL spectrum of CdS nanowires at 10 K. The best fit results based on Varshni empirical equation support our assignment of FX. Temperature dependent integrated peak intensity and linewidth of FX were analyzed by means of a two-step quenching process model and well fitted by Toyozawa's theory. All fitted results including thermal activation energy, LO-phonon energy were close to that observed in bulk CdS, indicating high quality of nanomaterial but also revealing its promising applications in photonics. © 2015 Elsevier B.V. Source

Yao D.,Tianjin University of Technology | Li W.,Tianjin University of Technology | Sun Y.,Universities of Inner Mongolia Autonomous Region | Wu H.,Universities of Inner Mongolia Autonomous Region | And 5 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2016

The effect of ZnO layer thickness t on the structure, static magnetic properties and high frequency properties is systemically studied for [Fe65Co35/ZnO(t)]50 multilayer films. The gradually increasing crystallinity of ZnO layer with increasing t is observed in the XRD patterns. The VSM measurements show good soft magnetic properties are obtained in these multilayer films, even though the ZnO layer is thick (up to 3.6 nm). For the typical sample with t=3.6 nm, an obvious in-plane anisotropy field and comparatively small coercivity are achieved, and high electric resistivity up to 12.6 mΩ cm is obtained. The measurement of permeability spectra indicates that the multilayers have an invariable ferromagnetic resonance frequency fr about 4.0 GHz; however, the initial permeability μi can be adjusted from 48 to 136 by decreasing t from 3.6 nm to 1.0 nm. The phenomenon that fr is almost invariable is the result of the decreasing saturation magnetization 4πMs and the increasing dynamic anisotropy field Hk-dyn with increasing t. For our samples, the real part (μ'2G) of complex permeability at f=2.0 GHz remains a high value beyond 90, while the imaginary part (μ"2G) keeps a low value below 1.55, indicating that these multilayer films are promising for application in high frequency range. © 2015 Elsevier B.V. All rights reserved. Source

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