VInH4在InP材料中的影响

在未掺杂和掺Ｆｅ的ＬＥＣ－Ｉｎ中用ＦＴ－ＩＲ测试到ＶＩｎＨ４的存在。已经证实该缺陷在ＬＥＣ－ＩｎＰ中普遍存在。经研究表明在掺Ｆｅ的ＩｎＰ中的ＶＩｎＨ４浓度比在未掺杂中的高。而在同一晶锭中其浓度分布是头部高,尾部低。讨论了其对未掺杂ＩｎＰ的电子特性和掺Ｆｅ的ＩｎＰ的补偿的影响,及其对ＩｎＰ热稳定性的影响。     

InP/GaAs低温键合的新方法

通过对 InP/GaAs 异质键合实验方法的研究,提出了包括表面活化处理、真空预键合和退火热处理的三步法,在350℃低温下实现了InP/GaAs异质材料的键合。界面电流 电压(I V)特性的研究表明,350℃样品的界面过渡层极薄,电子主要以隧穿方式通过界面,而450℃的扩散使得过渡层增厚,界面电流 电压特性可视为双肖特基二极管的反向串联。同时,对键合样品也进行了拉力测试,实验结果表明 450℃样品的键合强度优于350℃样品。最后,对InP/GaAs异质材料的键合机理进行了探讨。     

Cu/Zn扩散偶的实验研究

用铆钉法将块体铜和块体锌制成Cu／Zn扩散偶，经真空炉扩散处理后，在扩散偶Cu／Zn界面处形成一个既不同于铜也不同于锌的扩散层。实验表明，除扩散温度和时间对扩散层有影响外，扩散偶的几何尺寸对扩散层的形成也有影响。扩散偶中锌销子的直径越小，形成扩散溶解层的速度越快，扩散厚度越大。     

搅拌摩擦焊辅助Al/Zn/Mg接头扩散连接

对2mm厚的AZ31B镁合金和6061铝合金平板进行添加夹层Zn的搅拌摩擦诱导扩散连接实验。通过SEM,EPMA,XRD,拉伸实验和维氏硬度测试研究Al/Zn/Mg搭接接头显微组织和力学性能。结果表明:当旋转速率合适时,扩散层存在Al富集区,Al5Mg11Zn4层及Mg-Zn共晶区;而旋转速率较低时,扩散层存在残留的Zn层;旋转速率过大时,扩散层出现Al-Mg系金属间化合物。由于扩散层主要为金属间化合物,其显微硬度明显高于母材。Zn箔的加入提高了Al/Mg搭接接头的力学性能。断口观察分析表明,接头失效发生在靠近Al侧的扩散层上。     

吸附-扩散模型与溶解-扩散模型及其修正模型的相互关系

研究了吸附-扩散模型(ADM)与溶解扩散模型(SDM)及其修正模型的相互关系,对溶解-扩散模型(SDM)、扩展-溶解扩散模型(ESDM)、不完全的溶解扩散模型(SDIM)中参数作了进一步解释.吸附-扩散模型(ADM)的一级近似表达式与溶解-扩散模型(SDM)及其修正模型的数学形式和物理意义相似,验证了吸附-扩散模型(ADM)的正确性.     

SiNx薄膜的性质及其在开管扩Zn中的应用

采用PECVD方法制备了SiNx薄膜,用椭偏测厚仪、红外光谱仪和俄歇能谱仪研究了SiNx薄膜的性质.测试结果表明,SiNx薄膜的折射率随SiH4流量增加不断增大,当SiH4/NH3为38/8时,沉积SiNx薄膜的折射率为1.93,对应的Si/N比约为0.75.FTIR测试结果表明,随着SiH4/NH3流量的增加,N-H含量降低,Si-H含量升高,当SiH4/NH3为38/8时,SiNx薄膜的H含量最少.通过优化沉积条件和层厚度,将SiNx薄膜应用于InP材料的开管扩Zn中,并成功制备了平面结构的InP/InGaAs PIN探测器.     

InP量子点的掺杂及其光学性能

采用原位成核掺杂法合成了Li、Zn金属离子掺杂的InP量子点(分别记为Li: InP和Zn: InP), 并研究了掺杂剂对量子点的结构、尺寸和光学性能的影响。研究结果表明, Li⁺、Zn²⁺掺杂的InP量子点结晶度较高且尺寸均匀。虽然Li⁺掺杂未引起InP量子点的结构发生变化, Li⁺未进入InP晶格, 但是抑制了InP量子点的成核与长大, 使其吸收谱和荧光谱均发生大幅度的蓝移。Zn掺杂同样也抑制InP量子点的成核与长大, 并且形成InP/Zn₃P₂/ZnO复合核壳结构, 显著增强了InP量子点的荧光, 尤其是当Zn掺杂浓度(Zn/In原子比)为0.2时, InP量子点的荧光强度增加近100多倍, 这对短波长InP量子点的合成具有一定的参考价值。     

热压扩散焊接法制备Ti-Al复合电极材料及性能

采用热压扩散法制备Ti-Al复合电极材料, 并通过SEM、 四探针法、 EDS、 电化学工作站等测试手段 对样品的结构与性能进行表征。结果表明: 热压扩散焊接在压力6 MPa、 焊接温度550℃、 氩气中保温时间≥90 min 的条件下, 可以实现Ti和Al的冶金结合, 而且扩散反应层产物的变化过程是: TiAl→TiAl₂→TiAl₃; 复合材料的电化学性能较纯Ti的有所提高, 制备工艺条件对电化学性能的影响与对电阻率的影响一致; 在同等条件下, 复合材料的极化电位较纯钛下降37~54 mV, 其电流密度至少可提高59.29%, 电阻率仅为纯钛的1/10。     

HDPE/EVA/CB复合导电材料的研究

研究了HDPE/EVA/CB(炭黑)复合材料的导电性及正温度系数(PTC)特性,包括电阻-温度特性和电流-时间特性.发现在HDPE/CB复合材料中加入少量的EVA能降低室温电阻率、改善炭黑粒子的分散、增强PTC效应以及缩短材料的响应时间,并从基体的结晶性及炭黑在共混基体中分布的角度探讨了EVA组分对复合材料电性能影响的作用机理.     

新型氧化镍超电容器电极材料的研究

使用传统的水解方法制备了氢氧化镍胶体,在300℃下进行热处理后得到具有特殊材料微结构以及表面特性的超细氧化镍材料,电化学方法证明该材料制备的电极具有典型的电容性能,“准电容”比容量达到240F／g以上,优于普通的双电层电容器活性炭电容材料比容量。本文首次提出了电容器的正负极采用不同材料的新技术,有效的解决了电容器工作电位范围相对较窄的不足,并且明显的改善了电容器的大功率放电特性,是一种极具有发展潜力的储能器件。     

Infrared reflectance study of n-type InP grown by the LEC method

Infrared reflectance spectra of n-type InP were measured in the mid and far infrared region, using a FT IR spectrometer. Two reflectivity minima R_min and the corresponding frequencies ω_min were observed. A universal chart for determining the free-carrier concentration and mobility is presented. By utilizing the second minimum, the measurable limit of the carrier concentration was improved to 7 × 10¹⁶ cm^?3. The results are consistent with those obtained from Hall measurements.     

一种制备ZnO纳米颗粒的新方法

提出了一种制备ZnO纳米颗粒的新方法。在金属钠的液氨溶液中还原硝酸锌,所形成的金属Zn自然氧化而制得ZnO颗粒。为了研究表面修饰对产物形貌、粒径和性能的影响,制备了十二烷基磺酸钠（SDS）修饰的ZnO纳米颗粒。采用X射线粉末衍射仪（XRD）、透射电子显微镜（TEM）、傅立叶变换红外光谱仪（FT-IR）、热重及差热分析仪（TG-DTA）等手段对产物进行了表征。结果表明采用该方法可制得具有六方纤锌矿结构的ZnO颗粒,未修饰ZnO颗粒团聚较为严重;修饰的ZnO纳米颗粒呈棒状,分散较好。红外和热分析表明SDS修饰在了ZnO纳米颗粒表面。测试了所制备ZnO颗粒的紫外可见吸收（UV-Vis）和光致发光（PL）谱,均出现了ZnO的特征谱带。提出的方法也适用于制备其它金属或氧化物纳米材料。     

A model for diffusion of beryllium in InGaAs/InP heterostructures

This study reports on Be diffusion from a Be-doped (3×10¹⁹ cm⁻³) In_0.53Ga_0.47As layer sandwiched between undoped InP layers grown by gas source molecular beam epitaxy. To explain the obtained experimental depth profiles, a kick-out model of substitutional interstitial diffusion mechanism, involving neutral Be interstitials for the InGaAs epilayer and singly positively charged Be interstitials for the InP epilayers, is proposed. Using the boundary conditions at the heterojunctions and taking into account the built-in electric field, Fermi level and bulk self-interstitial generation/annihilation effects, we obtained a good agreement between the simulated and experimental data.     

Thermal diffusion in nanostructured porous InP

Nanostructured porous InP samples were prepared by electrochemical anodic dissolution of InP for various current densities and etching periods. The samples were characterized by SEM and photoluminescence (PL) where a blue shift was observed in PL. Thermal properties studied by photoacoustic (PA) spectroscopy revealed one order decrease in thermal conductivity of porous InP compared to the bulk. Further it is shown that the thermal conductivity of porous InP decreases with decrease in size of the particles.     

Borosiloxane boron diffusion for p-emitter formation on n-type silicon wafers

Thermal boron diffusion, which forms highly doped and shallow p-emitters on phosphor-doped silicon wafers, is one of the primary processes in commercial-scale production of n-type cells. Here, we report on the use of nontoxic and nonvolatile borosiloxane sols as the spin-on boron source. In comparison to the tribromide (BBr₃) boron diffusion that is applied in the production of most commercial n-type cells, borosiloxane boron diffusion may have potential advantages in terms of cost, safety, operability, etc. The borosiloxane sols studied here were formed from a cross-linking reaction between boron acid and a mixture of two types of silicon alkoxides, methyltriethoxysilane (MTEOS) and dimethyldiethoxysilane (DMDEOS). The MTEOS/DMDEOS ratio was found to be the key factor determining the synthetic period, net structure, thermal transformation property, and coating behavior of the borosiloxane sols. In combination with the spin-coating method, the performance of borosiloxane boron diffusion into phosphor-doped silicon wafers (1–3 Ω·cm) was systematically investigated by varying the borosiloxane composition (boron/silicon or MTEOS/DMDEOS ratio) and the diffusion process parameters (temperature, ambience, and period of individual sub-steps), and by relating them to the resulting sheet resistance and boron doping profile. The results show that under the diffusion conditions in conventional cell production lines, the formed p-emitters can have variable sheet resistance in the range of 35–582 Ω/□ and boron doping depth of 100–300 nm.     

Investigation on deep level defects in rapid thermal annealed undoped n-type InP

Deep levels in rapid thermal annealed Pd/n-InP Schottky contacts have been studied using deep level transient spectroscopy. It is observed that the as-deposited Pd/n-InP Schottky sample exhibit two deep levels with activation energies of 0.53 and 0.70 eV. In samples annealed at 400 °C, three deep levels having activation energies 0.18, 0.30 and 0.86 eV below the conduction band are observed and for samples annealed at 500 °C, four deep levels with activation energies 0.33, 0.44, 0.70 and 0.82 eV are observed. Fourier transform infrared spectroscopy measurements have been carried out on undoped as-deposited and annealed InP wafers at 300, 400 and 500 °C. The measurements revealed high concentration of hydrogen complexes in the form of V_InH₄ existing in InP wafer. The results show that V_InH₄ complex annihilates with increase of annealing temperature and results in the formation of P _In ²⁺ and V _P ⁺ defects at 0.70 and 0.44 eV, respectively.     

A novel method for determination of diffusion coefficient of corrosive species in organic coatings by EIS

The diffusion coefficients of water and Cl^– ion in epoxy coatings on aluminum alloys LY12 were investigated by electrochemical impedance spectroscopy (EIS). The key task in the present work remained in the model fitting of EIS data, from which coating capacitance was derived and was used to calculate water diffusion coefficient by the commonly used capacitance method. Moreover, by the fitting analysis of EIS, appropriate equivalent electrical circuits (EEC) were proposed for different immersion stage. After that the initiation time for the appearance of each EEC was known. These times were correlated to the required times for penetrants arrival through the coating at metal interface. Then the diffusion coefficient was calculated from these characteristic required times in the case of Fickian diffusion. This novel method is defined as required time method in this work. It was shown that comparative values were obtained by using both the capacitance and required time methods for the water diffusion coefficient. Even more, the diffusion coefficient of Cl^– ion calculated by required time method was very close to that reported in the literature (measured by nuclear magnetic resonance (NMR) technique).     

Simple method to synthesize novel mesoporous zinc oxide

Mesoporous ZnO microfans have been successfully synthesized from the ZnS microfans by the thermal treatment. The morphology, specific surface area, and optical properties of ZnO microfans were analyzed by X-ray diffraction, scanning electron microscope, N₂ adsorption,and photoluminescence spectroscopy. Results reveal that ZnO microfans show good crystalline quality, high specific surface area, and excellent optical properties.     

A method of fabricating n-type thermoelements from galena concentrate

A process of fabricating n-type thermoelements by using abundantly available galena concentrate, including optimization of the sintering temperature and time, is reported in this paper. The results of variation of room temperature resistivity and thermoelectric power have been explained on the basis of inhomogeneities in the sample.