光学薄膜损伤的单光子吸收电离的电子雪崩模型

分析了实际光学薄膜与其块状材料在微观结构及宏观尺寸上的差异,指出了单光子吸收电离与雪崩倍增可分为两个相对独立的先后过程处理,提出了实际光学薄膜激光诱导损伤的单光子吸收电离引发电子雪崩模型,讨论了原初电子数密度与入射激光波长的关系,以及实际光学薄膜激光诱导损伤阈值与其原初电子数密度的关系,提出了确定原初电子数密度的实验方法。     

无损检测固体表面、次表面不均匀性和缺陷的激光光热偏转技术

本文介绍非接触无损检测固体物质表面、次表面不均匀性和缺陷的激光光热偏转技术,设计并建立了测量装置。文中列出了对光学薄膜弱吸收率的测量,对碳素纤维材料、光学薄膜表面激光损伤和对金属材料次表面模拟缺陷的成像检测等一些应用的结果。     

沉积温度对三倍频ZrO2薄膜能隙的影响

采用电子束蒸发沉积制备了不同基底温度的ZrO2单层薄膜.计算了薄膜在三倍频处的折射率、消光系数,分析了基底温度对薄膜带隙的影响及薄膜性质与损伤阈值的关系,得出了薄膜能隙随温度升高而降低,薄膜在三倍频处的损伤阈值与能隙成正比关系,这与薄膜损伤机理-多光子吸收、雪崩电离机理相符.     

影响InN材料带隙的几个关键问题

确定了InN材料的带隙值并研究了影响InN材料带隙变化的导带电学结构和几个关键因素,以解释当前用不同方法生长不同质量的InN材料时出现的各种不同带隙值.用光致发光、光吸收和光调制反射方法测量确定InN材料的带隙值约为0.7eV;探讨了InN材料带隙与温度的函数关系,并分析了影响InN材料带隙的导带电学结构和有关因素.影响InN材料带隙的主要因素有Moss-Burstein效应、深能级俘获现象以及N:In化学计量比等,得出在不同质量样品和不同生长条件下,3种因素均影响InN材料的带隙值,但所起的作用却不尽相同.     

激光预处理对增透膜阈值的影响

激光预处理是提高光学薄膜激光损伤阈值的有效方法之一。本文就激光预处理前后增透膜损伤阈值的变化、破斑深度的变化、膜层中电场分布情况，分析了激光预处理对阈值的影响及原因。     

光学多层膜减小电场强度的一种新设计方法

制作 损伤阈值光学薄膜不仅需要沉积工艺有所突破,而且需要膜系设计也有所改进,用于减少强激光对薄膜的损伤因素。本文提出了一种计算机算法用于改善光学多层膜内驻波场分布,肖弱电场强度对薄膜的损伤。其物理概念清清晰,理论推导,算法编程实用简单。     

毫秒激光致光学薄膜损伤阈值的测试与分析

根据ISQ-11254分别测量了脉宽1 ms,波长1 064 nm激光作用下TiO2/SiO2高反膜、增透膜的损伤阈值,结合高分辨率CCD和光学显微镜观测了损伤形貌,分析了毫秒量级激光损伤光学薄膜的损伤机理.结果表明:脉宽1 ms激光作用下TiO2/SiO2增透膜的损伤阈值为高反膜的2.4倍,损伤区域为若干分离的损伤点...     

一维功能梯度材料声子晶体弹性波带隙研究

应用平面波展开法研究了由功能梯度材料周期复合而成的一维声子晶体中存在的弹性波带隙特征,并得到第一阶带隙归一化起始频率、截止频率和宽度随功能梯度材料表面材料常数、指数因子和组分比变化的关系图。并对功能梯度材料声子晶体与常规材料声子晶体帯隙特征进行了比较,结果表明,功能梯度材料声子晶体较常规材料声子晶体在相同范围内能够出现更多阶带隙结构。这些结果为功能梯度材料声子晶体在工程实际中的广泛应用提供了理论依据和指导。     

1μm激光对光学薄膜的损伤

本文采用不同的高折射率薄膜材料，分别镀制了增透模和高反模，送往三个不同的实验室，在不同条件下进行了１μｍ的损伤阈值测试，对薄膜的弱吸收也进行了测试，并比较了不膜系结构、薄膜材料、吸收和薄膜缺陷密度对其激光损伤阈值的影响。     

非平衡磁控溅射类金刚石薄膜的激光损伤过程研究

类金刚石薄膜是一种很好的红外窗口表面增透保护材料,随着对其抗激光损伤特性研究的不断深入,越来越多的研究者都将研究的重点放在了如何提高其激光损伤阈值上。然而,不同沉积方法制备的薄膜由于其微观结构存在的差异,必然会导致破坏的过程有所不同。本文采用非平衡磁控溅射技术沉积的薄膜,对其损伤过程进行了深入的研究。结果表明：在不同的激光能量下,DLC薄膜出现不同的损伤形态,而这些与薄膜的缺陷、内应力以及薄膜与衬底的结合力密切相关。     

Investigation of the substrate effect for Zr doped ZnO thin film deposition by thermionic vacuum arc technique

ZnO is a fundamental wide band gap semiconductor. Especially, doped elements change the optical properties of the ZnO thin film, drastically. Doped ZnO semiconductor is a promising materials for the transparent conductive oxide layer. Especially, Zr doped ZnO is a potential material for the high performance TCO. In this paper, ZnO semiconductors were doped with Zr element and microstructural, surface and optical properties of the Zr doped ZnO thin films were investigated. Zr doped ZnO thin films were deposited thermionic vacuum arc (TVA) technique. TVA is a rapid and high vacuum deposition method. A glass, polyethylene terephthalate and Si wafer (111) were used as a substrate material. Zr doped ZnO thin films deposited by TVA technique and their substrate effect investigated. As a results, deposited thin films has a high transparency. The crystal orientation of the films are in polycrystal formation. Especially, substrate crystal orientation strongly change the crystal formation of the films. Substrate crystal structure can change the optical band gap, microstructural properties and deposited layer formation. According to the atomic force microscopy and field emission scanning electron microscopy measurements, all deposited layer shows homogeneous, compact and low roughness. The band values of the deposited thin film were approximately found as to be 3.1–3.4 eV. According to the results, Zr elements created more optical defect and shifted to the band gap value towards to blue region.     

Effect of laser flux density on ZnCdS thin films

Effect of laser flux density on the structural quality and optical properties of Zn_0.6Cd_0.4S thin films synthesized by ultraviolet pulsed laser deposition have been studied. The stoichiometric composition of this alloy was estimated using lattice constant calculated via XRD data. Surface morphology of the samples was examined using AFM. Optical properties were studied at room temperature by transmittance, absorbance, and photoluminescence measurements. Studies revealed that there is an improvement in the structural quality with increasing the laser flux density in some range. However, too high laser flux density could lead to the degradation in structural quality of thin film. It was observed from the PL data that with increase in laser flux density there is a decrease in the band gap. Transmission data shows a transmittance of more than 70% in the visible region. TEM investigation of the samples reveals that the particles are spherical in shape with average diameter of 15 nm.     

Properties of BGO thin films under the influence of gamma radiation

It is important to know the behaviour of materials under the influence of radiation for the effective design of novel sensor systems. Optical properties of bismuth germinate (Bi₄Ge₃O₁₂—BGO) thin films were investigated in terms of their perception to gamma radiation exposure. An Edwards E306A vacuum thermal coating system was used for thin films deposition. BGO films with a thickness of 200 nm were exposed to a disk-type ¹³⁷Cs gamma radiation source with an activity of 370 kBq. Optical properties of the films were investigated using CARY IE UV-Visible Spectrophotometer. Calculated optical band gap for as-deposited BGO thin film was 1.95 eV. Gamma radiation induced changes in the optical properties of thin films, which could be explained by the variation in the degree of disorder. From the density-of-state model, it is known that optical band gap decreases with an increasing degree of disorder of the amorphous phase.Electrical properties of BGO thin films were recorded in real time using a low power capacitive interface system with a high resolution, which is based on Delta-sigma modulator. At doses from 0 to 1.5 mGy little if any changes in the capacitance were measured. This could be explained by co-existence of two processes, namely creation and annihilation of defects under the influence of radiation. After a threshold dose of 1.5 mGy creation of defects becomes more prevailing and the BGO film capacitance has gradually increased in value from 2.97 pF to 7.09 pF after irradiation with a 2.44 mGy dose.     

节瘤缺陷对薄膜热力损伤的有限元分析

在多层介质薄膜中,节瘤缺陷是影响薄膜激光损伤的关键因素。为了理解节瘤缺陷对薄膜激光损伤的影响,以热传导理论为依据,通过有限元方法模拟了多层介质薄膜中的节瘤缺陷在激光辐照下的热力响应,分析了节瘤缺陷的大小和深度对热力响应的灵敏度。发现大而浅的节瘤缺陷有较高的热力响应灵敏度,因此,消除直径较大的膜层表面附近的缺陷有助于提高薄膜抗激光损伤的能力。     

Comparative study of physical properties of vapor chopped and nonchopped Al2O3 thin films

Aluminium oxide being environmentally stable and having high transmittance is an interesting material for optoelectronics devices. Aluminium oxide thin films have been successfully deposited by hot water oxidation of vacuum evaporated aluminium thin films. The surface morphology, surface roughness, optical transmission, band gap, refractive index and intrinsic stress of Al₂O₃ thin films were studied. The cost effective vapor chopping technique was used. It was observed that, optical transmittance of vapor chopped Al₂O₃ thin film showed higher transmittance than the nonchopped film. The optical band gap of vapor chopped thin film was higher than the nonchopped Al₂O₃, whereas surface roughness and refractive index were lower due to vapor chopping.     

缺陷对β-Ga2O3薄膜的结构和光学特性的影响

采用射频磁控溅射技术和后期退火在蓝宝石衬底上成功制备了β-Ga₂O₃薄膜。借助于X射线衍射(XRD)、拉曼散射光谱(Raman)、X射线光电子能谱(XPS)、以及二次离子质谱(SIMS)研究了缺陷对β-Ga₂O₃薄膜的结构和光学特性的影响。结果表明,未退火的Ga₂O₃薄膜呈现非晶态,随高温退火时间逐渐增加,非晶Ga₂O₃薄膜逐步转变为沿(-201)方向择优生长的β-Ga₂O₃薄膜。所有Ga₂O₃薄膜在近紫外到可见光区的平均透过率都高达95%,β相Ga₂O₃薄膜的光学带隙比非晶态薄膜增加~0.3 eV,且随退火时间的增加,β-Ga₂O₃薄膜的光学带隙也随之变宽。此外,发现非晶Ga₂O₃薄膜富含氧空位缺陷,高温退火处理后,β-Ga₂O₃薄膜中的氧空位浓度明显降低,但蓝宝石衬底中的Al极易扩散至Ga₂O₃薄膜层,并随退火时间的增加Al浓度明显增加,氧空位的降低和Al杂质的增加是导致β-Ga₂O₃薄膜光学带隙变宽的主要原因。     

Microstructural properties of electrochemically synthesized ZnSe thin films

In this study, we report the electrosynthesis of zinc selenide (ZnSe) thin films on indium-doped tin oxide-coated glass substrates. The deposited ZnSe thin films have been characterized for structural (X-ray diffraction), surface morphological (scanning electron microscopy), compositional (energy dispersive analysis by X-rays), photo luminescence property, and optical absorption analysis. Formation of cubic structure with preferential orientation along the (111) plane was confirmed from structural analysis. In addition, the influence of the deposition potential on the microstructural properties of ZnSe is plausibly explained. The optical properties of ZnSe thin films are estimated using the transmission spectrum in the range of 400–1200 nm. The optical band gap energy of ZnSe thin films was found to be in the range between 2.52 and 2.61 eV. Photoluminescence spectra were observed at blue shifted band edge peak. The morphological studies depict that the spherical and cuboid shaped grains are distributed evenly over the entire surface of the film. The sizes of the grains are found to be in the range between 150 and 200 nm. The ZnSe thin film stoichiometric composition was observed at optimized deposition condition.     

Growth of Cu2SnS3 thin films by solid reaction under sulphur atmosphere

Cu₂SnS₃ thin film have been synthesized by solid state reaction under vapour sulphur pressure at 530 °C, during 6 h, via a sequentially deposited copper and tin layers Cu/Sn/Cu…Sn/Cu/Sn. The structure and the composition were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Probe Micro Analysis (EPMA). X-ray diffraction revealed that as the deposited film crystallizes in the cubic structure and the crystallites exhibit preferential 111 orientation of the grains. Moreover, EPMA analysis confirmed that the obtained film is stoichiometric. The SEM study shows the presence of spherical particles of ≈100-120 nm diameters. The optical absorption coefficient and band gap of the film were estimated by means of transmission and reflection optical measurements at room temperature. A relatively high absorption coefficient in the range of 10⁴ cm⁻¹ was indeed obtained and the band gap value is of the order of 1.1 eV. On the other hand, the electrical conductivity of Cu₂SnS₃ film prepared in the present experiment is suitable for fabricating a thin film solar cell based on not cheaper and environmental friendly material.