铜蒸气激光器热透镜特性的分析与测量

本文用光束偏转法和干涉法分别测量了以熔石英为窗口材料的铜蒸气激光器及其窗口的热透镜效应。实验表明：铜蒸气激光器工作时的等效热透镜由放电管内气体负透镜和窗口的正透镜复合而成，理论分析与实验结果相符。     

参数设置对噪声等效温差（NETD）测试影响分析

噪声等效温差是一个用以标志红外热成像系统灵敏度的广泛使用的参数.在实际测试中各种参数的设置会对噪声等效温差的测试结果产生较大的影响,主要有积分时间、增益、背景温度等.详细分析了噪声等效温差及各参数的理论模型并在此基础上进行了实验与分析,定量地给出了各参数对噪声等效温差的影响,这为正确测试噪声等效温差提供了重要的参考依据.     

深度饱和三极管等效电路模型分析

运用现代电子仿真实验平台和传统实际实验方法，尝试通过对共发射极放大器电路静态和动态工作参数的测量，分析深度饱和的三极管的动态等效模型。并运用三极管的动态等效模型分析，当放大器输入和输出耦合电容改变时，对输入与输出信号之间相位位移的影响，通过仿真平台和传统方法实验结果分析两者结果一致，从而进一步阐明深度饱和三极管的等效模型。     

连续波HF化学激光器小信号增益的测量

描述了测量连续波HF化学激光器小信号增益空间分布的装置。给出了CL—9喷管的几个跃迁增益分布的测量结果并对实验结果及误差作了简单讨论。     

红外成像系统噪声等效温差数字图像测试方法

噪声等效温差是评价红外成像系统性能的关键参数之一。数字图像在红外成像系统的显示与记录中得到越来越广泛的应用,但原有的噪声等效温差均是基于模拟图像进行测试。提出基于数字图像的红外成像系统噪声等效温差测试方法,用最小二乘法拟合信号传递函数,用三维噪声模型分析并计算系统噪声,给出了噪声等效温差的计算方法。搭建测试环境,分别对线列扫描红外成像系统和焦平面阵列红外成像系统进行测试,并对测试数据与标称值进行对比、分析。     

凝视型红外光电成像系统主要参数的实验室测评分析

综合阐述了凝视型红外光电成像系统实验室主要参数测评,并对最小可分辨温差MRTD、系统调制传递函数MTF和噪声等效温差NETD等参数的测试方法进行了陈述,给出了具体测试实验过程和实验结果,对影响测试结果的因素进行了分析.     

异轴角散射法测量湿蒸气参量的方法研究

为了实时监测汽轮机末级湿蒸气中水滴大小分布和浓度的变化,指导汽轮机的安全经济运行和锅炉给水量,减小湿蒸气对汽轮机的影响,提出了一种以CCD为探测器、测量湿蒸气参量的异轴角散射方法;根据模拟汽缸的结构和参量建立数学模型,并进行了仿真分析,得出水滴群质量中间半径、水滴数浓度和尺度分布参量的变化对散射比的影响规律;分别对不同工况下的湿蒸气进行了实验测量;仿真和实验结果变化趋势基本一致。结果表明,利用异轴角散射法测量湿蒸气参量变化是可行的。该研究对湿蒸气参量以及其它微粒的监测是有帮助的。     

分子束外延系统束流系综理论分析

分子束外延（MBE）生长薄膜材料是一种非平衡态生长，生长过程主要由分子束流和晶体表面反应动力学控制。分子束流控制对生长的影响很大，真空蒸发理论导出的平衡蒸气压模型是目前描述分子束流的主要模型之一，但在实际应用中，模型在高蒸气压条件下对束流的描述存在较大偏差，制约生长的薄膜的化学组分均匀性和结构的单晶完整性的提高。本文系统研究了MBE生长HgCdTe薄膜过程的束流情况，采用系综理论，建立巨正则理论模型模拟束流情况，实验表明，相比平衡蒸气压模型，该模型能更准确的描述分子束流的本征物理行为。     

化学蒸气光谱实时监测系统的信噪比分析

在建立化学蒸气辐射传输方程的基础上，着重讨论了一蒸气谱线具有洛化茨线形时傅里叶变换光谱仪（ＦＴＩＲ）的信噪比（ＳＮＲ）和噪声等效浓度程长积（ＮＥＣＬ）。给出了光谱系统综合性能参数：噪声等效光谱辐射度（ＮＥＳＲ）表示的目标云团浓度程长积（ＣＬ）的灵敏度方程。最后对模拟剂ＤＭＭＰ的化学蒸气光谱的分辨率选取进行了讨论。     

空间噪声等效温差测试方法研究

噪声等效温差(NETD)是热像仪主要性能参数之一。对空间噪声等效温差(spatial-NETD)的测试方法进行研究,完善空间噪声等效温差测试技术,并对测试结果进行分析比较,指出空间噪声等效温差测试的重要性,为空间噪声等效温差在热像仪性能测试中的应用提供依据。     

VLP／CVD低温硅外延

研究了VLP／CVD低温硅外延生长技术,利用自制的VLP／CVD设备,在低温条件下,成功地研制出晶格结构完好的硅同质结外延材料。扩展电阻、X射线衍射谱和电化学分布研究表明,在低温下（T＜800℃）应用VLP／CVD技术,可以生长结构完好的硅外延材料,且材料生长界面的杂质浓度分布更陡峭。     

The incorporation of hydrogen into III-V nitrides during processing

Hydrogen is readily incorporated into GaN and related alloys during wet and dry etching, chemical vapor deposition of dielectric overlayers, boiling in water, and other process steps, in addition to its effects during metalorganic chemical vapor deposition or metalorganic molecular beam epitaxial growth. The hydrogen is bound at defects or impurities and passivates their electrical activity. Reactivation of passivated shallow donors in the nitrides occurs at 450-550°C, but evolution from the crystal requires much higher temperatures (≥800°C for GaN).     

Calculation of the optimum vapor pressure for stoichiometry in PbTe and PbSnTe

Optimum vapor pressure for stoichiometry in growth of PbTe and PbSnTe has been calculated. The result is in a good agreement with the experimentally obtained ones for vapor pressure controlled Bridgman growth and liquid phase epitaxy. The procedure of calculation follows that performed earlier for GaAs, which assumed the equality of the chemical potentials of the volatile element in gas, liquid and solid phases. Also it is pointed out that the nonequilibrium reactions of interstitial Te atoms with Pb vacancies forming anti-site Te, as well as Te precipitations, take place at the highest applied Te vapor pressure region.     

Chemisorption sensing and analysis using silicon cantilever sensor based on n-type metal-oxide-semiconductor transistor

This paper presents a silicon cantilever sensor based on n-type metal-oxide-semiconductor transistor for chemical sensing and analysis using the chemisorption-induced surface stress sensing principle. The cantilever is along the 〈1 0 0〉 crystal orientation of the (1 0 0) silicon, and the transistor channel is parallel to as well as located at the rear part of the cantilever to obtain high stress sensitivity. The gold film deposited on the bottom surfaces of cantilevers is chemically functionalized with a self-assembled monolayer of 4-mercaptobenzoic acid via the Au-SH covalent bonding. The vapor phase chemical sensing experiments with acetone, ethanol, nitroethane and water vapor as targets are performed. The observed response differentiation implies that the molecular interaction mechanisms between different chemical molecules are different.     

Very Long SiC‐Based Coaxial Nanocables with Tunable Chemical Composition

We present a simple process for the fabrication of very long SiC‐based coaxial nanocables (NCs). The versatility of this technique is confirmed by the ability to change the chemical composition of the NC outer layers from silica to carbon and boron nitride. The NCs consist of a SiC core approximately 30 nm in diameter with lengths up to several hundred of nanometers. The thickness of the coating is in the range 2–10 nm. The morphology and structural characterization of the NCs is investigated by scanning electron microscopy (SEM) and high‐resolution transmission electron microscopy (HRTEM), respectively, and their chemical composition is probed by electron energy loss spectroscopy (EELS). A vapor–solid growth mechanism is proposed to explain the growth of SiC‐based NCs of various chemical compositions, depending on the chemical nature of the vapor phase. Because of the large quantity of very long and interlaced NCs produced during the synthesis, the macroscopic aspect of the as‐grown material is like a self‐supported felt.     

Two-step fabrication of thin film encapsulation using laser assisted chemical vapor deposition and laser assisted plasma enhanced chemical vapor deposition for long-lifetime organic light emitting diodes

A thin film encapsulation layer was fabricated through two-sequential chemical vapor deposition processes for organic light emitting diodes (OLEDs). The fabrication process consists of laser assisted chemical vapor deposition (LACVD) for the first silicon nitride layer and laser assisted plasma enhanced chemical vapor deposition (LAPECVD) for the second silicon nitride layer. While SiN_x thin films fabricated by LAPECVD exhibits remarkable encapsulation characteristics, OLEDs underneath the encapsulation layer risk being damaged during the plasma generation process. In order to prevent damage from the plasma, LACVD was completed prior to the LAPECVD as a buffer layer so that the laser during LACVD did not damage the devices because there was no direct irradiation to the surface. This two-step thin film encapsulation was performed sequentially in one chamber, which reduced the process steps and increased fabrication time. The encapsulation was demonstrated on green phosphorescent OLEDs with I–V-L measurements and a lifetime test. The two-step encapsulation process alleviated the damage on the devices by 19.5% in external quantum efficiency compared to the single layer fabricated by plasma enhanced chemical vapor deposition. The lifetime was increased 3.59 times compared to the device without encapsulation. The composition of the SiNx thin films was analyzed through Fourier-transform infrared spectroscopy (FTIR). While the atomic bond in the layer fabricated by LACVD was too weak to be used in encapsulation, the layer fabricated by the two-step encapsulation did not reveal a Si–O bonding peak but did show a Si–N peak with strong atomic bonding.     

Surface morphology dependent tungsten oxide thin films as toxic gas sensor

Tungsten oxide (WO₃) films are of great importance in gas sensing technology due to its selectivity towards toxic gases. In this paper, structural, morphological and compositional properties of spray deposited and chemical vapor deposited WO₃ thin films were investigated using XRD, TEM, SEM, EDAX and Raman spectroscopy. These films have monoclinic crystal structure; and a filamentous network surface for spray deposited films whereas small flake-shaped microstructure was observed on the surface of chemical vapor deposited films. These films were studied for their gas sensing ability towards toxic gases like ammonia (NH₃) and sulphur dioxide (SO₂) as a function of temperature and concentration. Response-recovery characteristics were studied by varying gas concentration. The spray deposited films displayed higher gas response than the chemical vapor deposited films whereas the later exhibited lower optimum operating temperature as well as faster response and recovery. A correlation between the morphological, compositional, electrical and gas sensing properties of these films is also established.     

Small signal analysis of source vapor control requirements forAPCVD

A method for small signal operating point analysis of the stability of chemical source vapor flow from liquid source vapor generators (bubblers) is presented. The analytical technique allow's quantification of the relative effect of changes in the flow, pressure, and temperature operating conditions of the vapor generator on the vapor output of the generator. Application of the analysis to ({tetraethylorthosilicate≡TEOS)+{trimethylphosphite ≡TMPi}+({trimethyl borate≡TMB}+{O₃≡ozone) based atmospheric pressure chemical vapor deposition (APCVD) processes yields example stability criteria for the bubbler control parameters. Examination of 5-wt%-B/4-wt%-P BPSG pre-metal dielectric (PMD), and SiO ₂ intermetal dielectric (IMD) processes show that variances in the bubbler temperature, ΔT, bubbler head space pressure, ΔP_HS, and carrier nitrogen flow, ΔQ_N2 affect the source vapor flow variance, ΔQ_ν, in the ratio of about 4.3:2.8:1 respectively. Film-doping and film-depth range-method uniformity specifications of ±0.1 wt% and ±2% require bubbler parameter control limits of: ΔT<0.25°C, ΔP_HS⩽6 torr, and ΔQ_N2⩽0.3% of operating point flow     

多壁碳纳米管定向生长参数的研究

研究了利用微波等离子体化学气相沉积法制备碳纳米管时各种工艺参数的影响。在化学气相沉积中催化剂起着至关重要的作用,为分析催化剂对碳纳米管生长情况的影响,采用常用的催化剂Fe和Ni作对比实验,并利用扫描电子显微镜表征手段分析不同催化层对碳纳米管生长情况的影响,发现使用Fe催化层在较高温度下,碳纳米管生长形貌较Ni催化层要好。而沉积温度在制备碳纳米管的过程中也起这重要的作用,所以实验针对不同沉积温度进行碳纳米管生长,结果发现600℃左右温度较适合碳纳米管生长。