热丝辅助MW-ECRCVD制备a-Si:H薄膜及硅-氢键合模式变化的研究

采用热丝辅助微波电子回旋共振化学汽相沉积(MW ECR-CVD)系统制备氢化非晶硅(a-SiH)薄膜.实验证明在原有的MW ECR-CVD基础上加入热丝辅助系统能有效提高a-SiH薄膜的沉积速率并大幅改善薄膜的稳定性;薄膜的沉积速率随着沉积压强的增加和热丝温度的上升而增加.通过光致衰退实验,将样品衰退前后的红外吸收谱图进行基线拟合和高斯函数拟合,计算得到薄膜的氢含量基本不发生变化,但Si-H与Si-H2组态的相对含量改变.     

氢化非晶硅薄膜光衰退稳定性的影响因素

用热丝辅助微波电子回旋共振化学气相沉积制备样品,通过红外吸收谱图和光衰退图,分析影响a-SiH薄膜光衰退稳定性的因素一方面,非晶硅网格中氢含量、氢硅键合方式以及氢的运动情况均对非晶硅材料的稳定性起着十分重要的作用,另一方面,在非晶硅的基体上生长少量微晶硅,可提高薄膜的稳定性.最终希望能通过两者的结合来探讨如何制备高光敏性和低光致衰退的非晶硅薄膜.     

热丝辅助MW ECR CVD法高速沉积优质氢化非晶硅薄膜

我们用热丝辅助MW ECRCVD系统,在热丝温度分别为0、1350、1400、1450、1500、1600和1700℃时制备出a-SiH薄膜.通过膜厚测定,红外光谱分析光、暗电导测量等手段,分析了其沉积速率、光敏性及光学带隙的变化规律.结果表明沉积速率和薄膜质量均得到明显的提高,沉积速率超过3nm/s,光暗电导之比提高到6×105.找到最佳辅助热丝温度为1450℃.通过对带隙值的分析,发现当带隙值在1.6～1.7范围内时,薄膜几乎都具有105以上的光暗电导之比.     

MW-ECR制备的氢化非晶硅光电特性研究

通过对热丝辅助微波电子回旋共振(HW-MW-ECRCVD)法制备的氢化非晶硅(a-SiH)薄膜进行暗电导与温度关系的测试,可得到暗电导激活能(Ea),并研究了Ea与a-SiH薄膜光敏性(σph/σ d)的关系;发现随着Ea的增大,费米能级位置下移,缺陷态密度减少,薄膜的光敏性变好.     

热丝辅助ECR-CVD制备a-Si:H薄膜的红外和光致衰退研究

采用热丝辅助MWECR-CVD系统制备出了a-SiH薄膜.应用傅立叶红外仪测量了薄膜的红外谱,用共面蒸铝电极法测量了薄膜的光电导.通过比较A样品(加入热丝)和B样品(未加热丝),得出在热丝辅助MWECR-CVD系统制备非晶硅薄膜过程中,热丝的光照对薄膜的抗衰退起到了关键作用,用该系统制备非晶硅薄膜,大大降低了薄膜中的总氢含量,提高了薄膜的稳定性,同时,Si-H键合体的摇摆模发生了红移.     

沉积条件对硅基薄膜非晶转微晶相变、沉积速率及其光电性能的影响(英文)

本文采用HWA-MWECR-CVD系统制备了微晶硅薄膜。研究了氢稀释比、反应压强以及微波功率对微晶硅薄膜非晶转微晶相变及其相关性能的影响。实验结果表明:当氢稀释比为94%、反应压强为1.5Pa以及微波功率为500W时,高质量的微晶硅薄膜可以被获得,如2.86*104的高光敏性,1nm左右的沉积速率以及8.9%的光致衰退速率等。     

HWCVD在玻璃衬底上沉积硅薄膜的研究

采用热丝化学气相沉积法在玻璃衬底上沉积硅薄膜,采用扫描电子显微镜、拉曼光谱分析表征样品的形貌和结晶性,较为系统地研究了硅烷浓度、衬底到热丝的距离对硅薄膜生长过程及各种性质的影响,结果表明,较高的衬底温度及较低的硅烷浓度有利于薄膜的结晶.     

双偏压辅助HF-PECVD沉积纳米金刚石薄膜工艺参数的AFM分析

采用双偏压辅助热丝一等离子增强化学沉积系统制备了纳米金刚石薄膜.采用AFM、SEM、Raman等考察了不同工艺条件对纳米金刚石薄膜形貌、粗糙度、内部结构等的影响.结果表明,热丝温度降低,所形成薄膜的晶粒尺寸变大,薄膜表面高低起伏较大,粗糙度也随之增大;随着射频输出功率的增大,等离子体轰击基底的能力增强,但过大的功率会使构成薄膜的晶粒变大;随着偏压的不断增大,氢离子体对薄膜表面的刻蚀程度逐渐增大,从而有利于形成纳米金刚石薄膜.     

热丝法制备多晶硅薄膜晶体取向及形态的研究

采用热丝化学气相沉积法(HWCVD),在很近的热丝与衬底距离(5 mm)下沉积多晶硅薄膜,研究了热丝温度、SiH4浓度对多晶硅晶粒取向和晶粒尺寸的影响规律。结果表明:当热丝温度在1400℃~1800℃变化,衬底温度225℃~320℃时,沉积出多晶硅薄膜的择优取向随温度升高的变化规律是(111)→(220)→(111);在低的灯丝温度(≈1450℃)和低的衬底温度(≈235℃)条件下,获得了晶粒横向尺寸大于1μm、垂直尺寸大于5μm的均匀致密的多晶硅薄膜。     

热丝法化学气相沉积金刚石系统温度分布与薄膜生长关系研究

对热丝化学气相沉积金刚石薄膜系统内的三种传热方式（传导、对流和辐射）进行了比较分析,数值计算了气相空间温度分布和衬底表面二维温度分布。采用热丝化学气相沉积工艺制备了金刚石薄膜,扫描电镜结果显示金刚石薄膜在不同生长区域呈现出与温度分布相关的微观结构与形貌。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.