Nickel and indium core-shell co-catalysts loaded silicon nanowire arrays for efficient photoelectrocatalytic reduction of CO_(2) to formate

Developing an efficient artificial photosynthetic system for transforming carbon dioxide and storing solar energy in the form of chemical bonds is one of the greatest challenges in modern chemistry.However,the limited choice of catalysts with wide light absorption range,long-term stability and excellent selectivity for CO_(2) reduction makes the process sluggish.Here,a core-shell-structured nonnoble-metal Ni@In co-catalyst loaded p-type silicon nanowire arrays(SiNWs)for efficient CO_(2) reduction to formate is demonstrated.The formation rate and Faradaic efficiency of formate over the Ni@In/SiNWs catalyst reach 58μmol h^(-1) cm^(-2) and 87% under the irradiation of one simulated sunlight(AM 1.5 G,100 mW cm^(-2)),respectively,which are about 24 and 12 times those over the pristine SiNWs.The enhanced photoelectrocatalytic performance for CO_(2) reduction is attributed to the rational combination of Ni capable of effectively extracting the photogenerated electrons and In responsible for the selective activation of CO_(2).

Enhanced Field Emission from Well-Patterned Silicon Nanoporous Pillar Arrays

The silicon nanoporous pillar array （Si-NPA） is synthesized by using hydrothermal etching method, and the electron field emission properties are studied. The results show that Si-NPA has a low turn-on field of 1.48 V/μm at the emission current of 0.1 μA and its field emission is relatively stable. The field emission enhancement of Si-NPA is believed to originate from its unique morphology and structure. Our finding demonstrates that the Si-NPA is a promising candidate material for field emission applications.

Fabrication of Through Micro-hole Arrays in Silicon Using Femtosecond Laser Irradiation and Selective Chemical Etching

We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the chemical reaction of the femtosecond laser-induced structure change zone and hydrofluoric acid solution. The morphologies of the through micro-holes and micro-hole arrays are characterized by using scanning electronic microscopy, The effects of the pulse number on the depth and diameter of the holes are investigated. Honeycomb arrays of through micro-holes fabricated at different laser powers and pulse numbers are demonstrated.

Optical Absorption Enhancement Effects of Silver Nanodisk Arrays in the Application of Silicon Solar Cell

Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation （DDA）,we study the absorption and scattering properties of two-dimensional square silver nanodisks （2D SSN） arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.

Silicon Field Emission Arrays Coated with CN_x Thin Films

Arrays of silicon micro\|tips were made by etching the p\|type (1 0 0) silicon wafers which had SiO 2 masks with alkaline solution. The density of the micro\|tips is 2×10 4 cm -2 . The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly. The CN x thin film, with the thickness of 1.27μm was deposited on the silicon micro\|tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X\|ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12.6 % and O: 17.9 %. The silicon arrays coated with CN x thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm 2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CN x thin films are likely to be good field emission cathode. The preparation and the characterization of the samples were discussed in detail.

The Effect of Silver-Plating Time on Silicon Nanowires Arrays Fabricated by Wet Chemical Etching Method

MACE (Metal-Assisted Chemical Etching) approach has drawn a lot of attentions due to its ability to create highly light-absorptive silicon surface. This method can generate numerous cylindrical shape microstructure on the surface of silicon like a forest, which is called “silicon nanowires arrays”. This structure can dramatically suppress both reflection and transmission at the wavelength range from 400 nm to near-infrared 1800 nm by increasing the propagation path of light. In this paper, ordered silicon nanowires arrays with a large area are prepared by wet chemical etching. It is demonstrated that the SiNWs (Silicon nanowires) arrays with different morphologies can be fabricated from monocrystalline silicon of a given orientation by changing silver-plating time. Excellent anti-reflection performance in broadband wavelengths and incident angle is obtained. The fabrication method and potential application of such SiNWs in the field of photoelectric detection have great value and can provide reference for further research in this field.

Ordered silicon nanorod arrays with controllable geometry and robust hydrophobicity

Highly ordered silicon nanorod（Si NR） arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality metal mask is to construct a non-close-packed template that can be removed with negligible damage to the mask. Hydrophobicity of Si NR arrays of different geometries is also studied. It is shown that the nanorod structures are effectively quasi-hydrophobic with a contact angle as high as 142°, which would be useful in self-cleaning nanorod-based device applications.

Maskless fabrication of quasi-omnidirectional V-groove solar cells using an alkaline solution-based method

Silicon passivated emitter and rear contact(PERC) solar cells with V-groove texture were fabricated using maskless alkaline solution etching with in-house developed additive. Compared with the traditional pyramid texture, the V-groove texture possesses superior effective minority carrier lifetime, enhanced p–n junction quality and better applied filling factor(FF). In addition, a V-groove texture can greatly reduce the shading area and edge damage of front Ag electrodes when the V-groove direction is parallel to the gridline electrodes. Due to these factors, the V-groove solar cells have a higher efficiency(21.78%) than pyramid solar cells(21.62%). Interestingly, external quantum efficiency(EQE) and reflectance of the V-groove solar cells exhibit a slight decrease when the incident light angle(θ) is increased from 0° to 75°, which confirms the excellent quasi omnidirectionality of the V-groove solar cells. The proposed V-groove solar cell design shows a 2.84% relative enhancement of energy output over traditional pyramid solar cells.

Si nanopillar arrays with nanocrystals produced by template-induced growth at room temperature

Well-aligned and closely-packed silicon nanopillar （SNP） arrays are fabricated by using a simple method with magnetron sputtering of Si on a porous anodic alumina （PAA） template at room temperature. The SNPs are formed by selective growth on the top of the PAA pore walls. The growth mechanism analysis indicates that the structure of the SNPs can be modulated by the pore spacing of the PAA and the sputtering process and is independent of the wall width of the PAA. Moreover, nanocrystals are identified by using transmission electron microscopy in the as-deposited SNP samples, which are related to the heat isolation structure of the SNPs. The Raman focus depth profile reveals a high crystallization ratio on the surface.

Silicon detector array for radioactive beam experiments at HIRFL-RIBLL

A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein.The detector system consists of five sets of three types of telescopes,which are successfully used to measure the angular distributions of both elastic scattering and breakup simultaneously, on the Radioactive Ion Beam Line in Lanzhou at Heavy Ion Research Facility in Lanzhou. This silicon detector array is used to measure the elastic scattering angular distributions of ^(11) Be on a ^(208) Pb target at E_(lab) = 140 and 209 MeV. A comparison of the Monte Carlo simulations with the experimental results shows a reasonable consistency.

Preparation, structural and electrical properties of zinc oxide grown on silicon nanoporous pillar array

Polycrystalline thick film of zinc oxide （ZnO） is grown on a unique silicon substrate with a hierarchical structure, silicon nanoporous pillar array （Si-NPA）, by using a vapour phase transport method. It is found that as-grown ZnO film is composed of closely packed ZnO crystallites with an average size of -10 μm. The film resistivity of ZnO/SiNPA is measured to be -8.9Ωcm by the standard four probe method. The lengthwise Ⅰ-Ⅴ curve of ZnO/Si-NPA heterostructure is measured. Theoretical analysis shows that the carrier transport across ZnO/Si-NPA heterojunction is dominated by two mechanisms, i.e. a thermionic process at high voltages and a quantum tunnelling process at low voltages.

Research and test of the adaptive quadrature demodulation technology for silicon micro-machined gyroscope

A program of adaptive quadrature demodulation is proposed to supply the gaps in the traditional analog detection technology of a silicon micro-machined gyroscope (SMG). This program is suitable for digital phase locked loop (DPLL) drive technology that proposed in other papers. In addition the program adopts an adaptive filtering algorithm, which selects the in-phase and quadrature components that are outputs of the DPLL of the SMG's drive mode as reference signals to update the amplitude of the in-phase and quadrature components of the input signal by iteratively. An objective of the program is to minimize the mean square error of the accurate amplitudes and the estimated amplitudes of SMG's detection mode. The simulation and test results prove the feasibility of the program that lays the foundation for the further improvement of the SMG's system performance and the implementation of the SMG system's self-calibration and self-demarcation in future.

Plasma jet array treatment to improve the hydrophobicity of contaminated HTV silicone rubber

An atmospheric-pressure plasma jet array specially designed for HTV silicone rubber treatment is reported in this paper. Stable plasma containing highly energetic active particles was uniformly generated in the plasma jet array. The discharge pattern was affected by the applied voltage. The divergence phenomenon was observed at low gas flow rate and abated when the flow rate increased.Temperature of the plasma plume is close to room temperature which makes it feasible for temperature-sensitive material treatment. Hydrophobicity of contaminated HTV silicone rubber was significantly improved after quick exposure of the plasma jet array, and the effective treatment area reached 120 mm？×？50 mm（length？×？width）. Reactive particles in the plasma accelerate accumulation of the hydrophobic molecules, namely low molecular weight silicone chains, on the contaminated surface, which result in a hydrophobicity improvement of the HTV silicone rubber.

Porous Silicon as a Carrier of Sensing Materials in Sensors

Novel potassium ion selective electrodes (K^+ISEs) and cDNA array sensors based on porous silicon (PS) have been developed.The calibration curve for the K^+ISEs is linear within a wide range of pK=2.0～6.0 with the slope of 56 mV per decade,which is near Nernst response.The response time and detection limit are within 31 s and 0.5μmol/L,respectively.The selective coefficient for Na^+ is-3.8,satisfies the requirement for the assay of blood potassium.The response variation is within 2 mV during 2 months.The binding capacity,the dynamic range and the detection limit of the DNA sensors were improved by replacing glass slide with PS substrates.The cDNA array sensors can bear 80℃of high temperature,75% of humidity,3.6 kLx of irradiation and keep stable within 10 days when they are exposed in air.Good performances of the K^+ISE and the cDNA array sensor are attributed to the large internal surface area and the easily modified microstructure of PS.

Design of MEMS C-Band Microstrip Antenna Array Based on High-Resistance Silicon for Intelligent Ammunition

In recent years, microstrip antennas have been more widely applied in satellite communications, mobile phones, unmanned aerial vehicle （UAV）, and weapons. A micro-electro-mechanical systems-based （MEMS-based） high-resistance silicon C-band microstrip antenna array has been designed for the intelligent ammunition. The center frequency is 4.5 GHz. A cavity has been designed in substrate to reduce the dielectric constant of silicon and high-resistance silicon has been used as the material of substrate to improve the gain of antenna. It is very easy to be manufactured by using MEMS technology because of the improved structure of the antenna. The results show that the gain of the antenna is 8 dB and voltage standing wave ratio （VSWR） is less than 2 by the analysis and simulation in high freauencv structure simulator （HFSS）.

基于温度传感阵列的TSV内部缺陷检测技术研究

在TSV三维集成领域,由于TSV内部缺陷的微小化和检测的不可接触性,寻找一个无损、灵敏且高效的内部缺陷检测方法尤为重要。针对这一挑战,提出了一种基于温度传感阵列的TSV内部缺陷检测方法。内部缺陷对TSV三维封装芯片的外部温度分布产生了影响,这些温度分布呈现出有规律的变化,每一种缺陷类型都会导致外部温度分布产生不同的偏差。利用温度传感阵列测量这些分布变化对缺陷进行有效的识别与分类。根据工作状态下的芯片产生的热信号以揭示其内部的缺陷信息,设计了基于温度传感阵列的检测系统。通过理论分析与仿真模拟,构建了模拟芯片工作状态下的温度分布和热变化的模型。实验中,以芯片样品的样本制备和测试平台搭建为基础,同时利用分类识别模型成功实现了对内部缺陷的有效分类,准确率高达99.17%。这种检测方法为高密度和微型化芯片的可靠性分析和故障诊断提供了一个经济高效的新途径。

孔形对基于硅微通道阵列的CsI:Tl闪烁屏性能影响的模拟

使用Geant4程序模拟了微孔形状对基于硅微通道阵列的CsI:Tl像素化X射线闪烁屏性能的影响。模拟的闪烁屏性能参数包括:闪烁光子数、底光输出、传输效率、n次全反射占比、调制传递函数(MTF)与空间分辨率的关系。模拟过程中设定微孔的形状分别为方形和圆形,两种孔形的微通道阵列周期相同,均为10μm。模拟结果显示:方形微孔的闪烁光子数优于圆形微孔,闪烁光子数正比于微孔横截面积;闪烁屏厚度小于400μm时,方形微孔的底光输出优于圆形微孔,厚度大于400μm时,圆形微孔的底光输出优于方形微孔;圆形微孔的传输效率优于方形微孔;厚度为40和200μm的方形微孔闪烁屏空间分辨率优于相同厚度的圆形微孔闪烁屏。制备了方形微孔的CsI:Tl闪烁屏样品,测量了其MTF与空间分辨率的关系,当MTF为0.1时,空间分辨率为22.6 lp/mm。

镍基阵列微针的薄胶微电铸制备工艺

阵列镍微针具有机械强度高、导电性好等优点,广泛应用于生物工程等领域。微电铸工艺凭借其复制精度高、适应性广等优点,已成为制备镍微针的可靠方法。然而,在微电铸工艺中,通常需要使用与铸层厚度相同的光刻胶模具,导致厚胶微电铸时面临微结构处存留残胶、胶层难以去除等问题。为了解决上述问题,获得尖端曲率半径为纳米尺度的阵列镍微针,我们提出了镍基阵列微针的薄胶微电铸制备工艺并进行实验验证。首先,利用(100)型单晶硅的各向异性刻蚀特性制备阵列锥坑硅模具;接着,在硅模具表面溅射一层厚度为200 nm的镍种子层;然后,使用光刻工艺制备微针支撑梁薄胶模具;最后,对硅模具进行微电铸,释放阵列镍微针。实验结果表明:本实验采用的方法可以在不损伤硅模具的前提下,得到尺寸平均偏差1.7μm、绝对位置平均偏差1.8μm、尖端平均曲率半径150 nm的阵列镍微针;使用厚度为~2μm的RFJ-60负性光刻胶作为微电铸的模具,成功制备出厚度为~24.3μm的阵列镍微针支撑梁。此外,通过将SiO2侧蚀量补偿进光刻掩膜版图形尺寸的方法,将镍微针相对尺寸误差降低至1%。结合微电铸工艺和单晶硅的各向异性刻蚀特性,能够高质量、高效率地制备阵列镍微针,为阵列镍微针的批量化制备奠定了基础。

硅纳米结构阵列:光热CO_(2)催化的新兴平台

人口的快速增长和高能源需求产业造成了严重的环境问题。太阳能等替代性的清洁能源对于缓解能源危机和温室效应至关重要。光催化是一种很有前途的方法,但它在转化率、效率和规模化方面存在局限性。光热催化则结合了光化学和光热效应,是在温和条件下有效催化化学反应的新概念。近年来,与传统的光热催化剂相比,硅纳米结构阵列在光热CO_(2)还原反应中表现出独特的催化性能优势。作为一种平台,它表现出优异的光收集能力、高比表面积以及多样化的材料复合选择。本文综述了光热催化CO_(2)转化的概念和原理,硅纳米结构阵列的功能,以及利用硅纳米结构阵列在光热催化CO_(2)转化方面的最新进展,最终将为高性能纳米结构阵列光热CO_(2)催化剂的发展方向提供指导。

基于CDs@SiNWs的光电化学免疫传感器构建及性能研究

采用金属辅助化学蚀刻法制备高定向硅纳米线阵列(silicon nanowire arrays, SiNWs),结合碳点(carbon dots,CDs)改性制备了一种新型无标记光电免疫传感器,用于心肌肌钙蛋白I(cardiac troponin I, cTnI)的检测。N型SiNWs作为光阳极,可获得强的光电信号基底响应。采用旋涂法将CDs负载于SiNWs表面,可以提高SiNWs对可见光的吸收能力,促进光生载流子分离,从而提高SiNWs的光电性能;同时,CDs为抗体连接提供了羧基活性位点。基于CDs@SiNWs的光电免疫传感器对cTnI的检测具有良好的线性范围(0.005~5.000 ng/mL)和较低的检出限(3.79 pg/mL)。所设计的光电化学(photoelectrochemical, PEC)免疫传感器具有良好的灵敏度、稳定性和重复性。该电极可实现无标签检测,为实现c TnI的即时检测提供了新的途径。