Electrical and dielectric properties of Al/p-Si and Al/perylene/p-Si type diodes in a wide frequency range

The perylene(C20H12) layer effect on the electrical and dielectric properties of Al/p-Si(MS) and Al/perylene/p-Si(MPS) diodes have been investigated and compared in the frequency range of 0.7 kHz–2 MHz. Experimental results show that C–V characteristics give an anomalous peak for two structures at low frequencies due to interface states(Nss) and series resistance(Rs). The increases in C and G/ω at low frequencies confirm that the charges at interface can easily follow an ac signal and yield excess capacitance and conductance. The frequency-dependent dielectric constant(ε) and dielectric loss(ε) are subtracted using C and G/ω data at 1.5 V. The ε and ε values are found to be strongly dependent on frequency and voltage, and their large values at low frequencies can be attributed to the excess polarization coming from charges at traps. Plots of ln(σac)–ln(ω) for two structures have two linear regions, with slopes of 0.369 and 1.166 for MS, and of 0.077 and 1.061 for MPS, respectively. From the C 2–V characteristics, the doping acceptor atom concentration(NA) and barrier height(ΦB) for Schottky barrier diodes(SBDs) of MS and MPS types are also obtained to be 1.484 × 1015 and 1.303 × 1015cm 3, and 1.10 and 1.13 eV, respectively.     

Comparative study of the electrical properties of Au/n-Si （MS） and Au/Si3N4/n-Si （MIS） Schottky diodes

In this paper,the electrical parameters of Au/n-Si(MS) and Au/Si3N4/n-Si(MIS) Schottky diodes are obtained from the forward bias current-voltage(I-V) and capacitance-voltage(C-V) measurements at room temperature.Experimental results show that the rectifying ratios of the MS and MIS diodes at±5 V are found to be 1.25 × 103 and 1.27 × 104,respectively.The main electrical parameters of the MS and MIS diodes,such as the zero-bias barrier height(ΦBo) and ideality factor(n),are calculated to be 0.51eV(I-V),0.53eV(C-V),and 4.43,and 0.65eV(I-V),0.70eV(C-V),and 3.44,respectively.In addition,the energy density distribution profile of the interface states(Nss) is obtained from the forward bias I-V,and the series resistance(Rs) values for the two diodes are calculated from Cheung's method and Ohm's law.     

Longitudinal,transverse,density-of-states,and conductivity masses of electrons in（001）,（101） and（111） biaxiallystrained-Si and strained-Si1-xGex

In this study,the electron effective masses,including longitudinal,transverse,density-of-states and conductivity effective masses,have been systematically investigated in(001),(101) and(111) biaxially strained Si and Si1-xGex.It is found that the effect of strain on the longitudinal and transverse masses can be neglected,that the density-of-states masses in(001) and(110) biaxially strained Si and Si1-xGex materials decrease significantly with increasing Ge fraction(x),and that the conductivity masses along typical orientations in(001) and(110) strained Si and Si1-xGex.are obviously different from those in relaxed Si.The quantitative results obtained from this work may provide valuable theoretical references to understanding strained materials physics and studying conduction channel design related to stress and orientations in the strained devices.     

CERN用于强子研究加速器系统离子注入的离子源GTS-LHC运行状况

The GTS-LHC ion source,designed and build by CEA Grenoble,was installed and commissioned at CERN in 2005.Since than the source has delivered oxygen and lead ion beams(O~(4 ) and Pb~(27 ) from the source,Pb~(54 ) from the linac)for the commissioning of the Low Energy Ion Ring(LEIR).Results of this operation and attempts to improve the source performance and reliability,and the linac performance will be presented in this paper.     

Coherent beam combination of adaptive fiber laser array with tilt-tip and phase-locking control

We present an experimental study on tilt-tip(TT) and phase-locking(PL) control in a coherent beam combination(CBC) system of adaptive fiber laser array.The TT control is performed using the adaptive fiber-optics collimator(AFOC),and the PL control is realized by the phase modulator(PM).Cascaded and simultaneous controls of TT and PL using stochastic parallel gradient descent(SPGD) algorithm are investigated in this paper.Two-fiber-laser-,four-fiber-laser-,and six-fiber-laser-arrays are employed to study the TT and PL control.In the cascaded control system,only one high-speed CMOS camera is used to collect beam data and a computer is used as the controller.In a simultaneous control system one high-speed CMOS camera and one photonic detector(PD) are employed,and a computer and a control circuit based on field programmable gate array(FPGA) are used as the controllers.Experimental results reveal that both cascaded and simultaneous controls of TT using AFOC and PL using PM in fiber laser array are feasible and effective.Cascaded control is more effective in static control situation and simultaneous control can be applied to the dynamic control system directly.The control signals of simultaneous PL and TT disturb each other obviously and TT and PL control may compete with each other,so the control effect is limited.     

Analysis of the excited bottom and bottom-strange states B1（5721）, B2*（5747）,Bs1（5830）, Bs2*（5840）, BJ（5840） and BJ（5970） of the B meson family

In order to make a further confirmation of the assignments of the excited bottom and bottom-strange mesons B1(5721),B2^*(5747),Bs1(5830)and Bs2^*(5840)and identify possible assignments of BJ(5840)and BJ(5970),we study the strong decay of these states with the 3P0 decay model.Our analysis supports the assignments of B1(5721)and B2*(5747)as the 1P'1 and 1^3P2 states,and Bs1(5830)and Bs2^*(5840)as the strange partners of B1(5721)and B2^*(5747).Besides,we tentatively identify the recently observed BJ(5840)and BJ(5970)as the 2^3S1 and 13D3 states.It is noted that these conclusions need further confirmation by measurements of the decay channels BJ(5840)→Bπand BJ(5970)→Bπ.     

White Organic Light-Emitting Devices Based on 2-（2-Hydroxyphenyl） Benzothiazole and Its Chelate Metal Complex

We present three kinds of organic light-emitting devices (OLED) fabricated to achieve the emission of bright and pure white light. Device A, with a double-layered structure using 2-(2-hydroxyphenyl) benzothiazole (HBT) and poly (N-vinylcarbazole) (PVK) as the emitting layer (EML) and the hole transport layer (HTL) respectively, could realize the blue-green light emission. Bis-(2-(2-hydroxyphenyl) benzothiazole)zinc (Zn(BTZ)2), synthesized with zinc acetate dihydrate and HBT to form a complex, is used as main EMLs in a similar structure to fabricate devices B and C. Bright and pure white light emissions can be obtained from device C which was fabricated with a green-white emitting host Zn(BTZ)2 and red dopant 5,6,11,12-tetraphenylnaphthacene (rubrene). The maximum quantum efficiency of device C could reach 0.63%, and the corresponding brightness and CIE coordinates were 4000cd/m^2 and (x=0.341, y=0.334) at the driving voltage of 20V.     

Brief of BES-Belle-CLEO-BaBar 2007 joint workshop on charm physics

The Institute of High Energy Physics of Chinese Academy of Sciences organized a workshop to establish closer contacts between experimentalists (theorists) involved in the studies of charm physics from both c and B communities. The workshop covers talks of physics analysis and its results from four electron-positron colliding experiments (BES, Belle, CLEO and BaBar). Presentations at the workshop are organized in the following sessions : (1) Hadron spectroscopy and new resonances; (2) D0-D0 mixing; (3) Charmonium decays; (4) Charm hadronic and (semi-)lcptonic decays; (5) QCD at low energy and τphysics; (6) Partial wave analysis and Dalitz analysis, MC generator and Tools; (7) Detector upgrade.     

Zero and controllable thermal expansion in HfMgMo_(3-x)W_xO_(12)

HfMgMo_(3-x)W_xO_(12) with x = 0.5, 1.0, 1.5, 2.0, and 2.5 are developed with a simple solid state method. With increasing the content of W, solid solutions of Hf Mg Mo3-xWx O12 crystallize in an orthorhombic structure for x≤2.0 and a monoclinic structure for x2.0. A near-zero thermal expansion(ZTE) is realized for HfMgMo_(2.5)W_(0.5)O_(12) and negative coefficients of thermal expansion(NCTE) are achieved for other compositions with different values. The ZTE and variation of NCTE are attributed to the difference in electronegativity between W and Mo and incorporation of a different amount of W, which cause variable distortion of the octahedra and softening of the MoO_4 tetrahedra, and hence an enhanced NCTE in the a- and c-axis and reduced CTE in the b-axis as revealed by Raman spectroscopy and x-ray diffraction.     

Ab initio study of structural,electronic,thermo-elastic and optical properties of Pt3Zr intermetallic compound

Structural,elastic,electronic and optical properties of the Pt3Zr intermetallic compound are investigated using first principles calculations based on the density functional theory(DFT)within the generalized gradient approximation(GGA)and the local density approximation(LDA).The Pt3Zr compound is predicted to be of cubic L12 and hexagonal D024 structures.The calculated equilibrium ground-state properties(lattice parameters a and c,bulk modulus B and its pressure derivative B',formation enthalpy ΔH)of the Pt3Zr compound,for both cubic and hexagonal phases,show good agreement with the experimental results and other theoretical data.Elastic constants(C11,C12,C13,C33,C44,and C55)are calculated.The predicted elastic properties such as Young's modulus E and shear modulus GH,Poisson ratioν,anisotropic ratio A,Kleinman parameter ξ,Cauchy pressure(C12-C44),ratios B/C44 and B/G,and Vickers hardness Hv indicate the stiffness,hardness and ductility of the compound.Thermal characteristic parameters such as Debye temperature θD and melting temperature Tm are computed.Electronic properties such as density of states(DOS)and electronic specific heat γ are also reported.The calculated results reveal that the Fermi level is on the psedogap for the D024 structure and on the antibonding side for the L12 structure.The optical property functions(real partε1(ω)and imaginary part ε2(ω)of dielectric function),optical conductivity σ(ω),refraction index n(ω),reflectivity R(ω),absorption α(ω)and extinction coefficients k(ω)and loss function L(ω)are also investigated for the first time for Pt3Zr in a large gamme of energy from 0 to 70 eV.     

A novel high performance TFS SJ IGBT with a buried oxide layer

A novel high performance trench field stop(TFS) superjunction(SJ) insulated gate bipolar transistor(IGBT) with a buried oxide(BO) layer is proposed in this paper. The BO layer inserted between the P-base and the SJ drift region acts as a barrier layer for the hole-carrier in the drift region. Therefore, conduction modulation in the emitter side of the SJ drift region is enhanced significantly and the carrier distribution in the drift region is optimized for the proposed structure. As a result, compared with the conventional TFS SJ IGBT(Conv-SJ), the proposed BO-SJ IGBT structure possesses a drastically reduced on-state voltage drop(Vce(on)) and an improved tradeoff between Vce(on)and turn-off loss(Eoff), with no breakdown voltage(BV) degraded. The results show that with the spacing between the gate and the BO layer Wo = 0.2 μm, the thickness of the BO layer Lo = 0.2 μm, the thickness of the drift region Ld = 90 μm, the half width and doping concentration of the N- and P-pillars Wn = Wp = 2.5 μm and Nn = Np = 3 × 1015cm-3, the Vce(on)and Eoffof the proposed structure are 1.08 V and 2.81 mJ/cm2with the collector doping concentration Nc = 1×1018cm-3and 1.12 V and1.73 mJ/cm2with Nc = 5 × 1017cm-3, respectively. However, with the same device parameters, the Vce(on)and Eofffor the Conv-SJ are 1.81 V and 2.88 mJ/cm2with Nc = 1 × 1018cm-3and 1.98 V and 2.82 mJ/cm2with Nc = 5 × 1017cm-3,respectively. Meanwhile, the BV of the proposed structure and Conv-SJ are 1414 V and 1413 V, respectively.     

A Practical Guide for X-Ray Diffraction Characterization of Ga（A1, In）N Alloys

Ca(In, Al)N alloys are used as an active layer or cladding layer in light emitting diodes and laser diodes, x-ray diffraction is extensively used to evaluate the crystalline quality, the chemical composition and the residual strain in Ca(Al,In)N thin films, which directly determine the emission wavelength and the device performance. Due to the minor mismatch in lattice parameters between Ca(Al, In)N alloy and a CaN virtual substrate, x-ray diffraction comes to a problem to separate the signal from Ca(Al,In)N alloy and CaN. We give a detailed comparison on different diffraction planes. In order to balance the intensity and peak separation between Ca(Al,In)N alloy and CaN, (0004) and (1015) planes make the best choice for symmetric scan and asymmetric scan, respectively.     

Hadron resonances as rovibrational states

A rovibrational model,including anharmonic,centrifugal,and Coriolis corrections,is used to calculate π,K,N, and Σ orbital and radial resonances.The four orbital excitations of the π meson correspond to the b(1235),π_2(1670),b_3(2030),and π_4(2250) resonances.Its first four radial excitations correspond to the π(1300),π(1800),π(2070),and π(2360) resonances.The orbital excitations of the K meson are interpreted as the K_1(1270),K_2(1770),K_3(2320),and K_4(2500) resonances;its radial excitations correspond to the K(1460) and K(1830) resonances.The N orbital excitations are identified with the N(1520),N(1680),N(2190),N(2220),and N(2600) resonances.The first four radial excitations of the N family correspond to the N(1440),N(1880),N(2100),and N(2300) resonances.The orbital excitations of the Σ baryon are associated with the Σ(1670),Σ(1915),Σ(2100),and Σ(2250) resonances,whereas its radial excitations are identified with the Σ(1660),Σ(1770),and Σ(1880) resonances.The proposed rovibrational model calculations show a good agreement with the corresponding experimental values and allow for the prediction of hadron resonances,thereby proving to be useful for the interpretation of excited hadron spectra.     

First principles investigation of protactinium-based oxide-perovskites for flexible opto electronic devices

The structural,elastic,mechanical,electronic,and optical properties of KPaO_3 and RbPaO_3 compounds are investigated from first-principles calculations by using the WIEN2 k code in the frame of local density approximation(LDA) and generalized gradient approximation(GGA).The calculated ground state quantities,such as lattice constant(α_0),ground state energy(E),bulk modulus(S),and their pressure derivative(B_p) are in reasonable agreement with the present analytical and previous theoretical results and available experimental data.Based on several elastic and mechanical parameters,the structural stability,hardness,stiffness and the brittle and ductile behaviors are discussed,which reveal that protactiniumbased oxide series of perovskites is mechanically stable and possesses weak resistance to shear deformation compared with resistance to unidirectional compression while flexible and covalent behaviors are dominated in them.The analysis of band profile through Trans-Blaha modified Becke-Johnson(TB-mBJ) potential highlights the underestimation of bandgap with traditional density functional theory(DFT) approximation.Specific contribution of electronic states is investigated by means of total and partial density of states and it can be evaluated that both compounds are(Γ-Γ) direct bandgap semiconductors.All fundamental optical properties are analyzed while attention is paid to absorption and reflection spectra to explore extensive absorptions and reflections of these compounds in high frequency regions.The present method represents an influential approach to calculating the whole set of elastic,mechanical,and opto-electronic parameters,which would conduce to the understanding of various physical phenomena and empower the device engineers to implement these materials in flexible opto-electronic applications.     

Effects of the 3d transition metal doping on the structural,electronic, and magnetic properties of BeO nanotubes

First-principles calculations have been performed on the structural, electronic, and magnetic properties of seven 3d transition-metal(TM) impurities(V, Cr, Mn, Fe, Co, Ni, and Cu) doped armchair(5,5) and zigzag(8,0) beryllium oxide nanotubes(BeONTs). The results show that there exists a structural distortion around the 3d TM impurities with respect to the pristine BeONTs. The magnetic moment increases for V- and Cr-doped BeONTs and reaches a maximum for Mn-doped BeONT, and then decreases for Fe-, Co-, Ni-, and Cu-doped BeONTs successively, consistent with the predicted trend of Hund’s rule to maximize the magnetic moments of the doped TM ions. However, the values of the magnetic moments are smaller than the predicted values of Hund’s rule due to the strong hybridization between the 2p orbitals of the near O and Be ions of BeONTs and the 3d orbitals of the TM ions. Furthermore, the V-, Co-, and Ni-doped(5,5) and(8,0) BeONTs with half-metal ferromagnetism and thus 100% spin polarization character are good candidates for spintronic applications.     

Production of bottomonium-like Z_b states in e-h and ultraperipheral h-h collisions

The photoproduction of the bottomonium-like states Z_b(10610) and Z_b(10650) via γ p scattering is studied within an effective Lagrangian approach and the vector-meson-dominance model. The Regge model is employed to calculate the photoproduction of Z_b states via the t-channel with π exchange. The numerical results show that the values of the total cross-sections of Z_b(10610) and Z_b(10650) can reach 0.09 nb and 0.02 nb, respectively,near the center-of-mass energy of 22 GeV. Experimental measurements and studies of the photoproduction of Z_b states near the energy region around W ■ 22 GeV are suggested. Moreover, with the help of eSTARlight and STARlight programs, we have obtained the cross-sections and numbers of events for Z_b(10610) production in electron-ion collisions(EIC) and ultraperipheral collisions(UPCs). The results show that a considerable number of Z_b(10610)events can be produced in the relevant experiments on EICs and UPCs. We have also calculated the rates and kinematic distributions for γp → Z_bn in ep and pA collisions via EICs and UPCs. The results will provide an important reference for the RHIC, LHC, EIC-US, LHeC, and FCC experiments in searching for bottomonium-like Z_b states.     

First-principles study of structural,electronic,and optical properties of cubic InAs_xN_yP_(1-x-y) triangular quaternary alloys

In this paper, we investigated the structural, electronic and optical properties of InAs, InN and InP binary compounds and their related ternary and quaternary alloys by using the full potential linearized augmented plane wave(FP-LAPW)method based on density functional theory(DFT). The total energies, the lattice parameters, and the bulk modulus and its first pressure derivative were calculated using different exchange correlation approximations. The local density approach(LDA) and Tran–Blaha modified Becke–Johnson(TB-m BJ) approximations were used to calculate the band structure.Nonlinear variations of the lattice parameters, the bulk modulus and the band gap with compositions x and y are found.Furthermore, the optical properties and the dielectric function, refractive index and loss energy were computed. Our results are in good agreement with the validated experimental and theoretical data found in the literature.     

Cosmological scenario based on particle creation and holographic equipartition

We propose a cosmological scenario that describes the evolution of the universe based on particle creation and holographic equipartition. The model attempts to solve the inflation of the early universe and the accelerated expansion of the present universe without introducing the dark energy from the thermodynamical perspective.Throughout the evolution of the universe, we assume that the universe consistently creates particles, and that the holographic equipartition is always satisfied. Further, we set the creation rate of particles proportional to H~2 in the early universe and to H in the present and late universe, where H depicts the Hubble parameter. Consequently, we obtain the solutions a(t) ∝ e~(αt/3) and a(t) ∝ t~(1/2) for the early universe and solutions a(t) ∝ t~δ and a(t) ∝ e~(Ht) for the present and late universe, respectively, where α and δ are the parameters. Finally, we obtain and analyze two important thermodynamic properties for the present model.     

Electronic,optical, and mechanical properties of BN,AlN, and InN with zinc-blende structure under pressure

In this work, the electronic, optical, and mechanical properties of BN, AlN, and InN under the action of pressure are calculated. For each of these compounds, the energy band structure, band gaps(E~L_g, E~Γ_g, E~X_g), refractive index(n),dielectric constants(ε_∞, ε_0), elastic constants(C_11, C_12, C_44), and relevant parameters such as bulk(B_u), shear(S_h), and Young's(Y_0) moduli are studied, and other important parameters such as bond-stretching(α), bond-bending(β) force constant, internal-strain parameter(ζ), effective charges(e~*_T, Z~*), anisotropy factor(I_s), Poisson's ratio(P_o), Cauchy ratio(C_a), the ductility index(μ_D), and linear compressibility(C0_) are also calculated. The effects of pressure on all studied properties are investigated. Our results are in good agreement with the available experimental and theoretical data for BN,AlN, and InN.     

One-range addition theorems for generalized integer and noninteger μ Coulomb, and exponential type correlated interaction potentials with hyperbolic cosine in position, momentum, and four-dimensional spaces

The formulae are established in position,momentum,and four-dimensional spaces for the one-range addition theorems of generalized integer and noninteger μ Coulomb,and exponential type correlated interaction potentials with hyperbolic cosine(GCTCP and GETCP HC).These formulae are expressed in terms of one-range addition theorems of complete orthonormal sets of Ψα-exponential type orbitals(Ψα-ETO),α-momentum space orbitals(α-MSO),and zα-hyperspherical harmonics(zα-HSH) introduced.The one-range addition theorems obtained can be useful in the electronic structure calculations of atoms and molecules when the GCTCP and GETCP HC in position,momentum,and four-dimensional spaces are employed.