P-channel Ge/Si Hetero-nanocrystal Based MOSFET Memory

The charge storage characteristics of P-channel Ge/Si hetero-nanocrystal based MOSFET memory has been investigated and a logical array has been constructed using this memory cell. In the case of the thickness of tunneling oxide T_ox=2nm and the dimensions of Si- and Ge-nanocrystal D_Si=D_Ge=5nm, the retention time of this device can reach ten years(~1×10~8s) while the programming and erasing time achieve the orders of microsecond and millisecond at the control gate voltage |V_g|=3V with respect to N-wells, respectively. Therefore, this novel device, as an excellent nonvolatile memory operating at room temperature, is desired to obtain application in future VLSI.     

硼预淀积对自组织生长Ge量子点尺寸分布的影响

研究了以不同B2H6流量预淀积硼对UHV/CVD自组织生长Ge量子点尺寸分布的影响。在适当的生长条件下,得到了尺寸分布很窄的均匀Ge量子点,用AFM对量子点的形貌进行观察,Ge量子点尺寸的涨落小于±3%,量子点的水平尺寸和高度分别为60nm和10nm,密度为8×109cm-2。实验结果表明,通过预淀积硼表面处理,可以得到尺寸分布很窄的量子点,以满足量子点光电器件方面应用的要求。     

Thermophysical properties data on molten semiconductors

Thermophysical properties of molten semiconductors are reviewed. Published data for viscosity, thermal conductivity, surface tension, and other properties are presented. Several measurement methods often used for molten semiconductors are described. Recommended values of thermophysical properties are tabulated for Si, Ge, GaAs, InP, InSb, GaSb, and other compounds. This review shows that further measurements of thermophysical properties of GaAs and InP in the molten state are required. It is also indicated that a very limited amount of data on emissivity is available. Space experiments relating to thermophysical property measurements are described briefly.Nomenclature Density - C _p Specific heat - Kinematic viscosity - Dynamic viscosity= - Thermal diffusivity - Thermal conductivity=C_p - Volumetric thermal expansion coefficient - Surface tension - d/dT Temperature coefficient of surface tension - g Gravitational acceleration - T Temperature - T Temperature difference - L Characteristic dimension     

光子计数成像探测器电荷感应层Ge薄膜特性研究

为了研究光子计数成像系统中感应电荷层Ge薄膜的制备工艺,改善光子计数成像系统的成像稳定性,采用直流磁控溅射法在熔石英衬底上制备了Ge薄膜,分析了工作气体Ar气通入量对Ge薄膜沉积速率的影响,利用表面轮廓仪及四探针表面电阻仪对样品分别进行了表面粗糙度及电学性能的表征。结果表明：随着Ar气通入量的增加,Ge薄膜沉积速率先上升后下降,在Ar气通入量为15sccm时,Ge薄膜的沉积速率出现极大值;Ge薄膜的表面粗糙度及薄膜电阻率均随着Ar气通入量的升高而增大;薄膜越厚,其电阻受氧化影响越小,电学性能越稳定。     

基于紫外光刻的双轴张应变Ge/SiGe多量子阱电吸收调制器北大核心CSCD

采用紫外光刻工艺(ultraviolet lithography technique,UVL),在互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)兼容的硅基平台上制作了基于悬空微桥结构在Ge/SiGe多量子阱材料中引入双轴张应变的低偏振相关电吸收调制器。利用拉曼光谱测试了器件引入双轴张应变的大小,并对器件在横电(transverse electric,TE)偏振和横磁(transverse magnetic,TM)偏振下的光电流响应、调制消光比和高频响应等性能进行了测试。器件的低偏振相关消光比在0 V/4 V工作电压下可达5.8 dB,3 dB调制带宽在4 V反向偏置电压时为8.3 GHz。与电子束光刻工艺(electron beam lithography technique,EBL)相比,采用UVL制作的器件在调制消光比、高频响应带宽等性能上略差一点,但具有曝光时间短、成本低和可大批量生产等优势,应用前景广阔。     

Precise Coulomb wave functions for a wide range of complex ?, η and z

A new algorithm to calculate Coulomb wave functions with all of its arguments complex is proposed. For that purpose, standard methods such as continued fractions and power/asymptotic series are combined with direct integrations of the Schrödinger equation in order to provide very stable calculations, even for large values of |η| or |ℑ(?)|. Moreover, a simple analytic continuation for is introduced, so that this zone of the complex z-plane does not pose any problem. This code is particularly well suited for low-energy calculations and the calculation of resonances with extremely small widths. Numerical instabilities appear, however, when both |η| and |ℑ(?)| are large and comparable or smaller than |ℑ(?)|.

Program summary

Title of program: cwfcomplexCatalogue number:ADYO_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADYO_v1_0Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions: noneComputers on which the program has been tested: DELL GX400Operating systems: Linux, WindowsProgramming language used: C++No. of bits in a word: 64No. of processors used: 1Has the code been vectorized?: noNo. of bytes in distributed program, including test data, etc.: 33 092No. of lines in distributed program, including test data, etc.: 3210Distribution format:tar.gzNature of physical problem: The calculation of Coulomb wave functions with all of their arguments complex is revisited. The new methods introduced allow to greatly augment the range of accessible ?, η, and z.Method of solution: Power/asymptotic series and continued fractions are supplemented with direct integrations of the Coulomb Schrödinger equation. Analytic continuation for is also precisely computed using linear combinations of the functions provided by standard methods, which do not follow the branch cut requirements demanded for Coulomb wave functions.Typical running time: N/AUnusual features of the program: none     

Ground state of the time-independent Gross-Pitaevskii equation

We present a suite of programs to determine the ground state of the time-independent Gross-Pitaevskii equation, used in the simulation of Bose-Einstein condensates. The calculation is based on the Optimal Damping Algorithm, ensuring a fast convergence to the true ground state. Versions are given for the one-, two-, and three-dimensional equation, using either a spectral method, well suited for harmonic trapping potentials, or a spatial grid.

Program summary

Program title: GPODACatalogue identifier: ADZN_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZN_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 5339No. of bytes in distributed program, including test data, etc.: 19 426Distribution format: tar.gzProgramming language: Fortran 90Computer: ANY (Compilers under which the program has been tested: Absoft Pro Fortran, The Portland Group Fortran 90/95 compiler, Intel Fortran Compiler)RAM: From <1 MB in 1D to ∼¹⁰² MB for a large 3D gridClassification: 2.7, 4.9External routines: LAPACK, BLAS, DFFTPACKNature of problem: The order parameter (or wave function) of a Bose-Einstein condensate (BEC) is obtained, in a mean field approximation, by the Gross-Pitaevskii equation (GPE) [F. Dalfovo, S. Giorgini, L.P. Pitaevskii, S. Stringari, Rev. Mod. Phys. 71 (1999) 463]. The GPE is a nonlinear Schrödinger-like equation, including here a confining potential. The stationary state of a BEC is obtained by finding the ground state of the time-independent GPE, i.e., the order parameter that minimizes the energy. In addition to the standard three-dimensional GPE, tight traps can lead to effective two- or even one-dimensional BECs, so the 2D and 1D GPEs are also considered.Solution method: The ground state of the time-independent of the GPE is calculated using the Optimal Damping Algorithm [E. Cancès, C. Le Bris, Int. J. Quantum Chem. 79 (2000) 82]. Two sets of programs are given, using either a spectral representation of the order parameter [C.M. Dion, E. Cancès, Phys. Rev. E 67 (2003) 046706], suitable for a (quasi) harmonic trapping potential, or by discretizing the order parameter on a spatial grid.Running time: From seconds in 1D to a few hours for large 3D grids     

离子束溅射制备Si／Ge多层膜研究

采用离子束溅射方法在Si衬底上制备Si／Ge多层膜，通过改变生长温度、溅射速率等因素得到一系列Si／Ge多层膜样品；通过X射线衍射、Raman散射等表征方法研究薄膜结构与生长条件的关系。在小束流（10mA）、室温条件下制备出界面清晰、周期完整的Si／Ge多层膜。     

Comparison of Bi3Fe5O12 film giant Faraday rotators grown on (111) and (001) Gd3Ga5O12 single crystals

Bismuth iron garnet (Bi₃Fe₅O₁₂, BIG) epitaxial thin films were grown on single crystal (Gd₃Ga₅O₁₂, GGG) (111) and (001) substrates by rf-magnetron sputtering technique. Processing parameters have been optimized to obtain high deposition rate (2.74 μm/h) and the surface rms roughness less than 10 nm. X-ray diffraction reveals films epitaxial quality: exclusive (111) or (001) orientation with narrow rocking curves and strong in-plane texture. Films possess low optical loss and magneto-optical Faraday rotation (FR) as high as 5 deg/μm at 677 nm wavelength. Comparative analysis of films grown on (111) and (001) substrates clearly shows significant superiority of BIG/GGG(001) film. For this film, the coercive field ∼100 Oe appears to be 2.5 times lower while the optical transmission to be 10% higher than that for BIG/GGG(111) film. Enhanced magneto-optical performance of BIG/GGG(001) films relies upon better accommodation of the film-to-substrate mismatch strain through the tetragonal BIG lattice distortions compared to the rhombohedral one in BIG/GGG(111) films.     

一种新型Si电子束蒸发器的研制及其应用研究

我们成功地设计出一种新型的Si电子束蒸发器,并将它应用于Ge/Si(111)量子点的生长.由于采用悬臂式设计,它完全克服了高压短路的问题.电子束蒸发器的性能试验表明,稳定输出功率可以控制输出稳定的Si束流.应用这种电子束蒸发器可以在700 ℃,成功沉积出平整的单晶Si薄膜.进一步的试验表明,在这种缓冲层表面可以自组装生长出Ge量子点.