Energy Gap and Electron Effective Mass in Chlorine Halide Superconductor at High Pressure

Dependences of the order parameter （ A ） and the electron effective mass （me^＊） on the temperature for the chlorine halide superconductor are determined in the present work. The high values of the pressure （p1 = 320 GPa andp2 = 360 GPa）, for which the critical temperature is equal to [Tc]m = 30.6 K and [Tc]p2 = 41.5 K, are taken into consideration. It is found that the dependence of the order parameter on the temperature deviates from the predictions of the classical Bardeen-Cooper-Schrieffer theory, due to the existence of the significant strong- coupling and retardation effects. The values of the order parameter, for the temperature close to zero Kelvin, are equal to [A（0）]p1 = 4.89 meV and [A（0）]p2 = 6.82 meV. The obtained results allowed next to calculate the dimensionless ratio R△ = 2A（O）/kBTc, which is equal to 3.71 and 3.81 in respect to pl and p2. In the last step, it is proven that the electron effective mass is weakly dependent on the temperature in the area of the existence of the superconducting state and reaches its maximum at the critical temperature. For the considered values of the max ＊ max pressure, we obtain [me^＊]pl^max = 1.69me and [me^＊]p2^max =1.78me, where the symbol me denotes the electron band mass.     

Mechanical and thermodynamic properties of the monoclinic and orthorhombic phases of SiC_2N_4 under high pressure from first principles

First principles calculations are preformed to systematically investigate the electronic structures, elastic and thermodynamic properties of the monoclinic and orthorhombic phases of Si C2N4 under pressure. The calculated structural parameters and elastic moduli are in good agreement with the available theoretical values at zero pressure. The elastic constants of the two phases under pressure are calculated by stress–strain method. It is found that both phases satisfy the mechanical stability criteria within 60 GPa. With the increase of pressure, the degree of the anisotropy decreases rapidly in the monoclinic phase, whereas it remains almost constant in the orthorhombic phase. Furthermore, using the hybrid density-functional theory, the monoclinic and orthorhombic phases are found to be wide band-gap semiconductors with band gaps of about 2.85 e V and 3.21 e V, respectively. The elastic moduli, ductile or brittle behaviors, compressional and shear wave velocities as well as Debye temperatures as a function of pressure in both phases are also investigated in detail.     

a——Si：H CCD的转移特性分析

本文从ａ－Ｓｉ：Ｈ的材料特性出发，采用更为精确的ａ－Ｓｉ：Ｈ带隙态分布模型计算了ａ－Ｓｉ：ＨＣＣＤ的转移特性，得出了ａ－Ｓｉ：Ｈ材料参数对ａ－Ｓｉ：ＨＣＣＤ的动态性影响的数值分析结果，理论结果表明，ａ－Ｓｉ：Ｈ材料带隙中局域态分布对ａ－Ｓｉ：ＨＣＣＤ的转移特性有非常大的影响，而且在高频下，ａ－Ｓｉ：Ｈ中的带尾态对ａ－Ｓｉ：ＨＣＣＤ转移特性的影响比深局域态要大。     

Transmission spectrum method to measure the photonic bandgap of hollow-core photonic crystal fiber

Photonic crystal fiber (PCF) is also known as microstruc- ture fiber (MSF). PCF typically consists of fused silica with an arrangement of periodic wavelength-scale air-holes run- ning along the full length of the fiber. PCF supports two guid- ance mechani…     

光子晶体的研究现状与最新进展

光子晶体是具有光子带隙的一种新型光学材料,由于其奇特的调节光子运动状态的特性,在光导纤维通信和光子计算机等领域中有着广泛的用途或潜在用途.本文系统地综述了光子晶体的产生、结构、制造和可能的应用,并介绍了光子晶体的最新研究进展.     

多晶硅TFT有源层晶粒间界的研究

由于多晶硅薄膜晶粒间界存在大量的悬挂键与缺陷，形成带隙能态，从而导致在有源层中形成载流子陷阱和杂质分凝，本文从微观方面解释悬挂键形成带隙能态的原因极其影响，并给出降低带隙密度的方法-氢化。     

CdS纳米晶颗粒薄膜的制备及其光学特性研究

采用化学浴沉积法,以CdCl2·H2O、CS(NH2)2、NH4Cl、NH3·H2O和去离子水作为反应前驱物,在不同的氨水浓度下制备CdS纳米晶颗粒薄膜.通过扫描电镜、X射线衍射、X射线能量色散谱、紫外-可见光透射光谱、椭圆偏振光谱等方法,研究了反应前驱物中氨水浓度对CdS纳米晶颗粒薄膜的表面形貌、晶体结构、S/Cd原子比、光透过率、光学带隙、折射率、消光系数和光学吸收边等物理性能的影响.结果表明:反应前驱物中氨水浓度在0.4～1.0mol/L范围内,可以在衬底上形成均匀致密的CdS纳米晶颗粒薄膜.随着氨水浓度的增加,CdS纳米晶的平均晶粒尺寸逐渐减少,S/Cd原子比逐渐增加,由富Cd型转变为富S型,禁带宽度逐渐增加.在500～1000 nm波段内,折射率的平均值为1.75;消光系数k小于0.07.     

不同材料构成声子晶体带隙特性研究

基于平面波展开法研究不同材料构成声子晶体带隙特性.数值模拟得到碳散射体与不同基体材料构成正方形声子晶体XY模式的能带结构,环氧树脂基体与不同散射体材料构成正方形声子晶体XY模式的能带结构,正方形和三角形结构声子晶体Z模式的能带结构.结果表明增加散射体与基体的密度比,更容易出现带隙,三角形结构相比正方形结构更易形成较宽带隙.研究结论为声子晶体器件制作提供理论依据.     

金属前驱体比例和硫化温度对Cu-Sn-S薄膜特性的影响

使用射频磁控溅射在镀Mo的玻璃基底上制备了Cu/Sn化学计量比为1.4 ～2.0的金属前驱体薄膜.经过400℃、450℃和500 ℃硫化后获得了一系列Cu-Sn-S薄膜.采用X射线衍射、X射线光电子能谱、拉曼光谱、原子力显微镜和紫外可见近红外分光光度计对样品进行了表征.结果表明:硫化温度与前驱体中Cu/Sn化学计量比对Cu-Sn-S薄膜的结构、化学组分和光学性能影响较大.当硫化温度为450℃,前驱体中Cu/Sn化学计量比为1.4∶1时,能得到近乎单一相、四方结构的Cu2SnS3薄膜,光学带隙为1.01 eV.过高的Cu/Sn化学计量比或硫化温度都会导致Cu3SnS4或Cu4SnS4的出现.     

CD/DVD-ROM马达驱动电路AAI5954设计开发

设计了一种可广泛应用于CD/DVD-ROM马达伺服系统的小功率马达驱动集成电路.简要描述了该电路的功能,特别介绍了一些主要电路功能模块的工作原理,并作了相应的数学推导.