Marine environment compatible antireflection coating with nanotop layer on silicon optics

Antireflection coating on silicon optics have crucial importance in thermal device working in 3.6–4.9 μm wavelength region. When the thermal device is used in marine environment, the optics face harsh saline weather condition compared to normal field environment. This deteriorates coated optics and to improve mechanical strength of the coating, a nanotop layer on the antireflection coating has been developed. In this paper a study has been carried out to improve marine environment compatibility by employing a nanolayer on the top of antireflection coating on silicon optics. Optimac synthesis method was used to design the multilayer stack on the substrate with germanium and IR-F625 as high/low refractive index respectively and the layer number was restricted to four layers. The top nanolayer was 60 ± 2 nm thick hafnium dioxide layer developed with ion assisted deposition (End–Hall) on the optics during coating process. The deposition of multilayer coating was carried out inside the coating plant fitted with cryo pump and residual gas analyzer. The evaporation was carried out at high vacuum (2–6 × 10⁻⁶ mbar) using electron beam gun and layer thicknesses were measured with crystal monitor. The average transmission achieved was 97% in the spectral band of 3.6–4.9 μm with a hardness of 9.7 GPa on the coated optics.     

A large area plastic scintillation detector with 4-corner-readout

A 760 mm × 760 mm × 30 mm plastic scintillation detector viewed by photomultiplier tubes(PMTs)from four corners has been developed, and the detector has been tested with cosmic rays and γ rays. A positionindependent effective time Teff has been found, indicating this detector can be used as a TOF detector. The hit position can also be reconstructed by the time from the four corners. A TOF resolution of 236 ps and a position resolution of 48 mm have been achieved, and the detection efficiency has also been investigated.     

Investigation of silicon doped by zinc ions with a large dose

The formation of nanoparticles in СZn-Si(100) implanted with ⁶⁴Zn⁺ ions using a dose of 5 × 10¹⁶ cm^–2 and an energy of 50 keV at room temperature with subsequent thermal processing in oxygen at temperatures ranging from 400 to 900°C is studied. The surface topology is investigated with scanning electron (in the secondary emission mode) and atomic force microscopes. The structure and composition of the near-surface silicon layer are examined using a high-resolution transmission electronic microscope fitted with a device for energy dispersive microanalysis. An amorphized near-surface Si layer up to 130 nm thick forms when zinc is implanted. Amorphous zinc nanoparticles with an average size of 4 nm are observed in this layer. A damaged silicon layer 50 nm thick also forms due to radiation defects. The metallic zinc phase is found in the sample after low-temperature annealing in the range of 400–600°C. When the annealing temperature is raised to 700°C, zinc oxide ZnO phase can form in the near-surface layer. The complex ZnO · Zn₂SiO₄ phase presumably emerges at temperatures of 800°C or higher, and zinc-containing nanoparticles with lateral sizes of 20–50 nm form on the sample’s surface.     

电流型大面积PIN探测器

研制了灵敏区面积为40,50和60mm,耗尽层厚度为200—300μm的电流型大面积薄型PIN半导体探测器,并对其物理性能进行了测量.测试和应用表明,这些探测器性能稳定,漏电流符合使用要求.与市场上的大面积PIN半导体探测器相比,这些探测器主要在几百伏偏压下工作在电流模式,但也可用于计数模式,而目前的商用产品仅适用于计数测量. 关键词： 半导体探测器 大面积 电流型     

Low cost CBD ZnS antireflection coating on large area commercial mono-crystalline silicon solar cells

Zinc sulfide is a wide band gap semiconductor with high refractive index and hence a promising material for antireflection coating over commercial silicon solar cells. In the present work, attempts have been made to improve the rate of deposition, uniformity of deposited film, stoichiometry, refractive index and the percentage of reflection, respectively, by proper optimization of molar percentage of different CBD ZnS bath chemical constituents and deposition conditions. High values of the rate of film deposition (19.6 Å), film uniformity (S.D.<1.8) and refractive index (2.35) along with a low percentage of average reflection (0.655) are achieved with proper optimization of ZnS bath. We have successfully fabricated 13.8% efficient large area (103 mm×103 mm) mono-crystalline silicon solar cells with CBD ZnS antireflection coating.     

具有纵向漏极场板的低导通电阻绝缘体上硅横向双扩散金属氧化物半导体器件新结构

为降低绝缘体上硅(SOI)横向双扩散金属氧化物半导体(LDMOS)器件的导通电阻,同时提高器件击穿电压,提出了一种具有纵向漏极场板的低导通电阻槽栅槽漏SOI-LDMOS器件新结构.该结构特征为采用了槽栅槽漏结构,在纵向上扩展了电流传导区域,在横向上缩短了电流传导路径,降低了器件导通电阻;漏端采用了纵向漏极场板,该场板对漏端下方的电场进行了调制,从而减弱了漏极末端的高电场,提高了器件的击穿电压.利用二维数值仿真软件MEDICI对新结构与具有相同器件尺寸的传统SOI结构、槽栅SOI结构、槽栅槽漏SOI结构进行了比较.结果表明:在保证各自最高优值的条件下,与这三种结构相比,新结构的比导通电阻分别降低了53%,23%和提高了87%,击穿电压则分别提高了4%、降低了9%、提高了45%.比较四种结构的优值,具有纵向漏极场板的槽栅槽漏SOI结构优值最高,这表明在四种结构中新结构保持了较低导通电阻,同时又具有较高的击穿电压.     

3D photonic crystals based on macroporous silicon: Towards a large complete photonic bandgap

Recently, a new three-dimensional photonic crystal consisting of two interpenetrating hexagonal pore sets was introduced. Here, we investigate the influence of possible experimental errors including shift, tilt and rotation of one pore set on the size of the bandgap theoretically and determine fabrication tolerances. A structure is fabricated in silicon using photo-electrochemical etching and subsequent focused ion beam milling. The change of the cross-section of the milled pores with pore depth is investigated and reflection measurements along different directions are performed indicating the low frequency edge of the photonic bandgap.     

A high-speed particle-detection in a large area using line-laser light scattering

We study the optical characteristics of a home-built line-laser surface light scattering system that detects sub-micron scale irregularities on a large area in high speeds. The sensitivity of the detection system, i.e. signal to noise (STN) ratio, is found to depend strongly on the detection angle. We find an optimal detection angle at 30°, at which STN ratio is maximized for 2500 nm silica particles on wafer surface. Experimental results of scattering intensity measurements from a smooth surface and from surfaces with spherical irregularities are in excellent agreement with corresponding theoretical model calculations. The line scan speed can be as high as ∼17 mm/s, while identifying the presence of a particle as small as 700 nm in a pixel area (∼15 μm × ∼17 μm). The presence of irregularities found by the line scan system is confirmed by confocal laser-scanning microscopy imaging. Due to unique advantages such as non-disruptiveness, high-speed over large area, and high sensitivity, this line scan system may be used as a surface inspection system that meets the requirements of recent flat panel display manufacturing environments.     

Multilayer-core fiber with a large mode area and a low bending loss

We present a single-mode multilayer-core fiber with a large mode area(LMA) and a low bending loss in this Letter. A low equivalent core-cladding refractive index difference is achieved by exploiting the multilayer structure. The multilayer structure has a better bending performance than a traditional step-index core and this structure also contributes to realizing different curved refractive index profiles that have a better bending performance. An index trench is also introduced to dramatically reduce the bending loss. The experimental results show that, at a wavelength of 1550 nm, the mode area of the fabricated fiber is about 215.5 μm~2 and the bending loss is 0.58 dB/turn at a 10 mm bending radius. The LMA and excellent bending performance can be obtained simultaneously with the proposed fiber.     

A large area gamma-ray imaging telescope system

We describe a large area Gamma-Ray Imaging Telescope System (GRITS), which will have the characteristics necessary for following up on the results from the Gamma-Ray Observatory (GRO) for energies >200 MeV. The detection technique is based on the measurement of the imaged light rings resulting from conversion of the incident gamma ray into an electron-positron pair which then produces the Cherenkov light in a large gas-filled pressure vessel. The instrument will be a pointed telescope for performing detailed studies of sources including improvement of positions, measurement of short term time variability, investigation of candidate sources searching for linear polarization and mapping of galactic structure.     

A system of units compatible with geometry

Alternative system of fundamental units: length, time, action, electrical charge is presented instead of the present one: length, time, mass and electrical current. It contains more quantities which are scalars under scalings. Then it is possible to recognize from the unit, what kind of a geometric quantity is a given physical quantity. This is the reason why the new system of units is called compatible with geometry.     

Production of a large area diffuse arc plasma with multiple cathode

An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. This device is comprised of a 42-mm diameter tubular chamber, multiple cathode which is radially inserted into the chamber, and a tungsten anode with a nozzle in its center. In argon/helium atmosphere, a large area and circumferential homogenous diffuse arc plasma, which fills the entire cross section surrounded by the cathode tips, is observed. Results show that the uniformity and stability of diffuse arc plasma are strongly related to the plasma forming gas. Based on these experimental results, an explanation to the arc diffusion is suggested. Moreover, the electron excitation temperature and electron density measured in diffuse helium plasma are much lower than those of constricted arc column, which indicates the diffuse helium plasma probably deviates from the local thermodynamic equilibrium state. Unlike the common non-transferred arc plasma devices, this device can provide a condition for axial-fed feedstock particles. The plasma device is attempted to spheroidize alumina powders by using the central axis to send the powder. Results show that the powder produced is usually a typical hollow sphere.     

Is a cosmological substratum compatible with relativity?

A cosmological substratum for energy propagation is defined in terms of a hypothesis by McCrea. It has been shown that the assumption of such a substratum for a uniformly expanding universe provides a cosmological interpretation of Special Relativity, and leads further to a theory of gravitation in terms of a universal acceleration field. Following a critical discussion of the bases of General Relativity, it is suggested that the proposed substratum model and its consequences are also compatible with the General Relativistic approach, providing that this is applied in a manner which recognises the centrally directed character of gravitational fields, and hence employs harmonic coordinates as proposed by Fock. It is shown that Fock's procedure leads to results which are consistent with the assumption of a uniformly expanding cosmological substratum. Finally, it is suggested that the cosmological substratum concept is also implied by the formulation of the Robertson-Walker metric.     

Active tuning of Si metasurface with large area

All-dielectric metasurfaces are usually limited because of their static functionality and small scale. In this paper, we use an easy nanofabrication technique to fabricate all-dielectric metasurfaces with the advantages of having dynamic tunability and a large area. Using an anodized aluminum oxide(AAO) template as an evaporation mask, a large-area metasurface embedded in polydimethylsiloxane(PDMS)(> 2 cm²) is fabricated. The metasurface exhibits remarkable electric dipole(ED) and ...     

High-intensity Si cluster ion emission from a silicon target bombarded with large Ar cluster ions

Secondary ions emitted from Si targets were measured with a quadrupole mass spectrometer under large Ar cluster and monomer ion bombardment. Incident ion beams with energies from 7.5 to 25 keV were used and the mean size of the Ar cluster ion was about 1000 atoms/cluster. Si_n⁺ ions with n values up to n = 8 were detected under Ar cluster ion bombardment, whereas Si cluster ions were scarcely detected under Ar monomer ion bombardment. These cluster ion yields showed the power law dependence on the cluster size.     

Features of photosensitive polycrystalline PbCdSe layers with a network-like structure

The features of photosensitive nanostructured polycrystalline Pb_xCd_1-xSe layers are studied by atomic force microscopy. A procedure is proposed, and changes in the concentration and conductivity type in the grain depth are studied by the data of local volt–ampere characteristics measured through a tunnel’s transparent barrier during the successive etching of the polycrystalline layer.     

Design of a large effective mode area photonic crystal fiber with modified rings

A photonic crystal fiber (PCF) is proposed that, through novel design, achieves an enhanced effective mode area. The PCF is composed of two concentric elliptical cores. The central core is un-doped silicon whilst the second, outer core region, is doped. The outer doped region is also bordered by lightly doped half ellipse segments. The effective mode area of the structure was calculated and compared with the mode area of conventional PCF's. Our results show that the mode area and chromatic dispersion are very sensitive to the geometry, dimensions and placement of the lightly doped segments. The chromatic dispersion, bend losses and the nonlinear coefficient are also numerically simulated and presented in this paper.     

Design of large mode area multicore photonic crystal fiber with a flat-top mode

A large mode area multicore photonic crystal fiber with a flattened fundamental mode is proposed in this paper. Another two kinds of single core fibers are also presented as comparison. The modal characteristics such as effective mode area and confinement loss are investigated using the finite element method. Numerical results show that a combination of flattened fundamental mode, large mode area and ultralow loss is obtained in the multicore fiber by introducing higher refractive index in the core region.     

Metrics compatible with a symmetric connection in dimension three

The problem of characterizing symmetric connections that are Levi-Civita connections of a pseudo-Riemannian metric is considered. A more or less complete solution of the problem in three dimensions is presented. In particular the single class of Levi-Civita connections whose metric is not determined up to a conformal factor by the curvature tensor alone is characterized in geometric terms.     

与消光式兼容的光度椭偏仪的原理

在PQSA式消光型椭偏仪基础上,把原来方位固定的1/4波片改为旋转波片就可以构成与消光式兼容的新型光度椭偏仪。本文讨论了这种光度椭偏仪的工作原理和计算公式。理论分析指出,这是一种完全的椭偏仪,能唯一地确定的符号,并在测量线偏光的时精度不会下降。文中还报告了进行原理性实验的结果。