Mostrando recursos 1 - 20 de 2.552

  1. Study of microstructure and electroluminescence of zinc sulfide thin film

    Liu, Z. H.; Wang, Y. J.; Chen, M. Z.; Chen, Z. X.; Sun, S. N.; Huang, M. C.; 黄美纯
    The electroluminscent zinc sulfide thin film doped with erbium, fabricated by thermal evaporation with two boats, are examined. The surface and internal electronic states of ZnS thin film are measured by means of X-ray diffraction and X-ray photoemission spectroscopy. The information on the relations between electroluminescent characteristics and internal electronic states of the film is obtained. And the effects of the microstructure of thin film doped with rare earth erbium on electroluminescence are discussed as well.

  2. Band structure of Si-based superlattices Si1-xSnx/Si

    Lu, T. Y.; 吕铁羽; Chen, J.; 陈捷; Huang, M. C.; 黄美纯
    The prospects of Si-based optical emitting materials are optimistic because the materials are compatible with silicon microelectronics technology. Therefore, many experimental and theoretical studies are directed to the design of direct band-gap Si-based materials. Based on the core state effect, the electronegativity differences effect of component atoms and the symmetry effect, Si-based superlattices Si1-xSnx/Si were designed. We found that Si0.875Sn0.125/Si is a direct bandgap material. In the density functional theory frame, the results of plane pesupotential method show that Si0.875Sn0.125/Si is a direct band-gap superlattice with minimum band-gap at Gamma point. We predict that the band gap of the material...

  3. Study of the band structure of the poly (para-phenylene) and its alkoxyl derivatives

    Chen, Z. B.; Huang, M. C.; 黄美纯
    In this paper, the one-dimensional band structures of poly (para-phenylene) (PPP) and its alkoxyl derivatives are calculated by an extended Huckel method (BICON-CEDiT code). The results of the band gaps E-g of these materials are in agreement with the available experimental data. In addition, we found the band gaps of PPP's alkoxyl derivatives become wider as the carbon atoms increase in alkoxyl side chain. The calculation indicates that the heteroatom and side groups have an obvious effect on the band structure of polymer, which is also consistent with the experimental results. The results are useful for synthesizing PPP with different...

  4. GW quasiparticle band structure of BaSe

    Chen, D. Y.; Lu, T. Y.; Huang, M. C.; 黄美纯
    The electron structure of barium's VIB compound is not clearly known yet. The main problem is that riot only the band gap calculated by using DFT (density functional theory) has a large discrepancy compared with experimental results, but also the theoretical values of band gap are inconsistent for different research groups. In order to resolve these problems, this paper makes the Green function-screened coulomb interaction quasiparticle theory (GW) calculation to get the quasiparticle band structure of BaSe. For the convenience of comparison, it deals with the systematic calculation of the energy band of BaSe by using the methods of local...

  5. Electronic and magnetic properties of 3d transition-metal-doped II-IV-V-2 chalcopyrite semiconductor

    Zeng, Y. Z.; Huang, M. C.; 黄美纯
    A systematic study based on ab initio calculation within local spin density approximation is carried out for material design of II-IV-V-2, chalcopyrite semiconductor (CdGeP2 and ZnGeP2) doped with 3d-TM (TM = V, Cr, Mn, Fe, Co and Ni). It is found that the ferromagnetic ( FM) state will be realized in V and Cr doped CdGeP2 and ZnCreP(2); for Mn, Fe and Co doped ones, the antiferromagnetic (AFM) states are more stable than FM states; whereas doped with Ni, the dilute magnetic semiconductor (DMS) shows unstable ferromagnetism. It is suggested that I-IV-V-2 chalcopyrite semiconductor doped with Cr is a candidate...

  6. Ab initio calculation of the formation energies of lithium substitutions in InSb

    Liu, H. Y.; Hou, Z. F.; Zhu, Z. Z.; Huang, M. C.; Yang, Y.; 黄美纯
    An ab initio calculation method with plane-wave basis and norm-conserving pseudopotentials was employed to investigate the electronic structures and formation energies of lithium substitutions in InSb in several cases. The changes of volumes, charge densities, band structures and electronic density of states for the lithium substitutions in InSb were discussed. The results show that the formation energies of lithium substitutions in zinc-blende InSb were all around -2.2 eV per Li atom, this results also indicate that the substitution of Li can not occur at the early stage of insertion when Li is not yet intercalated into the clearance space of...

  7. Electronic structure of ScN and YN: density-functional theory LDA and GW approximation calculations

    Lu, T. Y.; Huang, M. C.; 黄美纯
    The desirable physical properties of hardness, high temperature stability, and conductivity make the early transition metal nitrides important materials for various technological applications. To learn more about the nature of these materials, the local-density approximation(LDA) and GW approximation i.e. combination of the Green function G and the screened Coulomb interaction W, have been performed. This paper investigates the bulk electronic and physical properties of early transition metal mononitrides, ScN and YN in the rocksalt structure. In this paper, the semicore electrons are regarded as valance electrons. ScN appears to be a semimetal, and YN is semiconductor with band gap of...


    Wang, R. Z.; Huang, M. C.; 黄美纯
    Based on the linear muffin-tin orbital atomic-sphere approximation (LMTO-ASA) numerical calculations, we contrast the band eigenstates of the (GaAs)1 (AlAs)1 (001) superlattice with those of the zincblende Ga0.5 Al0.5 As alloy. We find that they can be described in a unified manner by the partial-wave states of the III and V group atomic planes. In this scheme, we analyze in more detail the correspondence relations of the band eigenstates of superlattice and zincblende alloy at points GAMMA, M(X), and R (L). The effects of the superlattice zone folding on the eigenstates are also discussed.


    Wang, R. Z.; Huang, M. C.; 黄美纯


    Ye, L.; Huang, M. C.; Zhu, Z. Z.; 黄美纯

  11. Ab initio study of electronic structure of strained Si1-x-yGexCy/Ge(001)

    Wu, L. Q.; Huang, M. C.; Li, S. P.; Zhu, Z. Z.; 黄美纯
    The ab initio pseudopotential method within the local density functional theory and virtual-crystal approximation is used to study the band gap of the Si1-x-yGexCy (y less than or equal to 0.09) alloys on a Ge(001) substrate. The heterojunction discontinuities are also investigated in the framework of the average bond energy theory in conjunction with the deformation potential method. The calculated results show that the energy gap still remains indirect and only a small amount of C could cause the energy gap to be shrunk significantly. The top of the valence bands of the strained Si1-x-yGexCy alloys on Ge(001) is significantly...

  12. First-principles calculations of the As-Ga electronic structures

    Zhang, Z. P.; Wu, C. X.; Shen, Y. W.; Huang, M. C.; 黄美纯
    The changes in the GaAs electronic structure due to the arsenic-antisite defect have been calculated by using LDF-LMTO-ASA method to a D-2d-symmetry-supercell (Ga15As17O square(32)), which contains 15 gallium atoms, 17 arsenic atoms and 32 empty spheres. The results show that the central As-Ga atom is antibonding with its nearest neighbor arsenic atoms and therefore induces gap states in GaAs. The gap states are composed of A(1)-like state and T-2-like state. The bonding properties of gap states have been analyzed in detail by using density of states (DOS) and combined coefficients of wavefunctions. Our results of E-A1 = E-v + 0.70...

  13. Theoretical electronic structure of oxide BaBiO3

    Shen, Y. W.; Zhu, Z. Z.; Huang, M. C.; 黄美纯
    In this paper, rye present a model simulation to understand the electronic structure of BaBiO3. By treating two types of Bi sites with different valence configurations (6s(2) 6p(3) 6d(0) and 7s(0) 6p(3) 6d(0)), the valence instability in BaBiO3 is simulated. We show that an LMTO-ASA calculation can then give a semiconducting feature for this material and a good estimation of the gap, which is 1.6 eV from the present model compared with 2.0 eV from experiments. The existence of Bi3+ sites reduces greatly the overlapping integrals between Bi-6s-O-2p states and reduces correspondingly their band widths. The band gap appears because...

  14. Electronic structure of Si1-xIVx/Si superlattices on Si (001)

    Chen, J.; Lu, T. Y.; Huang, M. C.; 黄美纯
    We have preformed systematical ab initio studies of the structural and electronic properties of short-period Si1-xIVx/Si (x = 0.125, 0.25, 0.5, IV=Ge, Sn) superlattices (SLs) grown along the [001] direction on bulls Si. The present calculations reveal that the Si0.875Ge0.125/Si, Si0.75Ge0.25/Si and Si0.875Sn0.125/Si are the Gamma-point direct bandgap semiconductors. The technological importance lies in the expectation that the direct gap Si1-xIVx/Si SLs may be used as components in integrated optoelectronic devices, in conjunction with the already well-established and highly advanced silicon technology.


    Chen, P.; Xie, Q. A.; Huang, M. C.; 黄美纯
    The thermodynamical properties of silver are calculated by using a recent model of many-body potential from lattice inversion method. The predictions of the phonon dispersion relation, the Gruneisen constant and the linear thermal expansion coefficient are all in coincidence with experiments. Of more importance, the present approach represents an efficient way of building potential functions capable of depicting the thermodynamics of metals for the Finnis-Sinclair model.


    Wang, Z. W.; Huang, M. C.; 黄美纯
    The self-consistent spin-polarized band-structure calculation of ferromagnetic compound MnBiAl in its low-temperature phase has been performed. In this paper the calculation results are given. Comparison with the results of MnBi is performed in order to find the effect on electronic structure by doping with Al.

  17. Quasiparticle band structure of BaS

    Lu, T. Y.; Chen, D. Y.; Huang, M. C.; 黄美纯
    We calculate the band structure of BaS using the local density approximation and the GW approximation (GWA), i.e. in combination of the Green function G and the screened Coulomb interaction W. The Ba 4d states are treated as valence states. We find that BaS is a direct band-gap semiconductor. The result shows that the GWA band gap (Eg-GW = 3.921 eV) agrees excellently with the experimental result (Eg-EXPT = 3.88 eV or 3.9 eV).

  18. Electronic properties of solid composed of Al12Ge clusters

    Zhu, Z. Z.; Tian, B.; Huang, M. C.; 黄美纯
    The ab initio pseudopotential local-density studies on the electronic structure and geometry of a theoretical solid are presented with Al12Ge cluster serving as the building block of the material. The results show that bulk material formed from cubic close-packing of Al12Ge clusters will eventually be an aluminum-like metal when lattice parameter of the solid and atomic geometry of the clusters are optimized by the crystal field.

  19. Electronic and magnetic properties of 3d transition-metal-doped III-V magnetic semiconductor

    Zeng, Y. Z.; Huang, M. C.; 黄美纯
    A systematic study based on an ab initio calculation within a local spin density approximation is applied to material design of GaAs- and GaP-base doped by 3d transition metals. It is found that the ferromagnetic (FM) state is ready to achieve by V-, Cr- and Mn-doped GaP and GaAs. (Ga, Cr)P and (Ga, Cr)As are the most promising candidates for high Curie temperature (above room temperature). In order to increase the Curie temperature, the Mg co-doped method is applied to (Ga, Mn)P and (Ga, Mn)As. By the co-doping, the energy difference between the antiferromagnetic state and the FM state is...

  20. Electronic structure of equilibrium-state TiNx films

    Zhang, Z. P.; Shen, Y. W.; Xu, W.; Huang, M. C.; 黄美纯
    By using LMTO-ASA method and supercelI approach, the self-consistent band structures for alpha-Ti, epsilon-Ti2N, and delta-TiN have been calculated. Moreover, alpha-Ti, epsilon-Ti2N, and delta-TiN were taken as three samples corresponding to TiNx films for x = 0, 0.5, 1.0. Then, according to the phase diagram of Ti-N and statistical supercell method, we have, for the first time to our knowledge. calculated the electronic structures of equilibrium-state TiNx films for all compositions of x < 1.0.

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