快速退火对PLD法制备SnS薄膜结构和光学性质的影响

利用脉冲激光沉积(PLD)法在玻璃基片上室温生长SnS薄膜,并在Ar气保护下分别在200,300,400,500,600℃对薄膜进行快速退火处理。利用X射线衍射(XRD)、拉曼光谱仪(Raman)、原子力显微镜(AFM)、场发射扫描电子显微镜( FE-SEM)、紫外-可见-近红外分光光度计( UV-Vis-NIR)、Keithley 4200-SCS半导体参数分析仪研究了快速退火温度对SnS薄膜的晶体结构、表面形貌以及有关光学性质和电学性能的影响。所制备的SnS薄膜样品沿(111)晶面择优取向生长,退火温度为400℃时的薄膜结晶质量最好。薄膜均具有SnS特征拉曼峰。随着退火温度的升高,薄膜厚度逐渐减小,而平均颗粒尺寸逐渐增大。不同退火温度下的SnS薄膜在可见光范围内的吸收系数均为105 cm-1量级,400℃时退火薄膜的直接带隙为1.92 eV。随着退火温度从300℃升高到500℃,电阻率由1.85×104Ω·cm下降到14.97Ω·cm。     

Sr0.75Ba0.25Nb2O6薄膜的PLD制备及其光学性能研究

本文采用脉冲激光沉积(PLD)方法在熔石英衬底上制备了Sr0.75Ba0.25Nb2O6(SBN0.75)光波导薄膜,采用Hitachi U-3410紫外-可见分光光度计对SBN0.75薄膜的透射谱进行测量,编程计算得到了薄膜折射率色散关系,同时得到SBN0.75薄膜的厚度和光学带隙分别为647.0nm和3.97eV。采用Metricon 2010棱镜耦合仪测量得到SBN0.75光波导薄膜中能激发的TE模式有4个,TM模式有3个。波长在632.8nm处薄膜的折射率为2.2818。并利用透射谱计算得出的薄膜的折射率和厚度值,根据波导理论导光模本征值的有效折射率表达式,对SBN0.75薄膜中能激发的导光模个数及其对应有效折射率进行图解,其结果与棱镜耦合仪所测得的结果非常吻合。     

金属纳米团簇复合薄膜Au/BaTiO3与Fe/BaTiO3的PLD制备及其光吸收特征

用脉冲激光沉积技术制备了掺杂纳米金属颗粒Au或Fe的BaTiO3复合薄膜.用透射电子显微镜和x射线光电子能谱表征了金属颗粒的形态和化学态.330-800nm范围的吸收谱研究表明,掺Au颗粒的BaTiO3薄膜在580nm附近有一个明显的共振吸收峰,而掺Fe颗粒的BaTiO3薄膜没有这样的吸收峰.用Mie散射理论对结果进行了分析.     

PLD制备的Cu掺杂SnS薄膜的结构和光学特性

利用脉冲激光沉积(PLD)在玻璃衬底上制备了Cu掺杂SnS薄膜.靶材是由SnS和Cu₂S粉末混合压制而成(Cu和Sn的量比分别为0%、2.5%、5%、7.5%和10%).利用X射线衍射(XRD)、拉曼光谱仪(Raman)、原子力显微镜(AFM)、紫外-可见-近红外分光光度计(UV-Vis-NIR)、Keithley 4200-SCS半导体参数分析仪研究了Cu掺杂量对SnS薄膜的晶体结构、表面形貌、光学性质和电学性能的影响.结果表明:所制备的SnS薄膜样品沿(111)晶面择优取向生长, SnS :5%Cu薄膜的结晶质量最好且具有SnS特征拉曼峰.随着Cu掺杂量的增大, 平均颗粒尺寸逐渐增大.不同Cu掺杂量的薄膜在可见光范围内的吸收系数均为10⁵ cm^-1数 量级.SnS :5%Cu薄膜的禁带宽度E_g为2.23 eV, 光暗电导率比值为2.59.同时, 在玻璃衬底上制备了p-SnS :Cu/n-ZnS 异质结器件, 器件在暗态及光照的条件下均有良好的整流特性, 并具有较弱的光伏特性.     

PLD法制备钴掺杂的氧化锌薄膜及其生长形貌和光学性能

用脉冲激光沉积(PLD)方法,在蓝宝石(0001)衬底上,制备了高度c轴取向的Zn1-xCoxO(x=0,0.02,0.05,0.07,0.1)薄膜。X射线衍射(XRD)分析表明,当钴掺杂量≤10mol%时没有出现其他杂峰,即没有出现分相。XPS分析显示Co离子在薄膜中以+2价的形式存在。进一步验证Co2+离子进入ZnO的晶格,对掺钴浓度不同的样品进行了UV-Vis吸收光谱测量。从UV-Vis吸收光谱可以看出随着掺杂浓度的增加,带隙逐渐变窄,证明Co2+取代了Zn2+而进入了ZnO晶格中。从原子力显微镜(AFM)形貌表征可以看出,随着钴掺杂量的提高,ZnO薄膜的表面起伏度有所减小,而且生长晶粒细化,从生长动力学的角度对生长形貌的改善进行了解释。     

Au-BaTiO3复合薄膜的脉冲激光沉积制备及其非线性光学效应

利用脉冲激光沉积技术制备了掺杂金纳米颗粒的钛酸钡复合薄膜Au-BaTiO3,用高分辨透射电镜和X射线光电子能谱对薄膜进行了表征。从透射电镜照片可以看出,制备的样品中金颗粒大小约为2~3 nm,呈球形,均匀分布在载体介质中。X射线光电子能谱给出了Ba3d、Ti2p和Au4f电子芯能级结合能,结果表明载体介质是以BaTiO3的形式存在,而Au以金属的状态掺杂其中。330~800 nm范围的线性吸收谱表明样品中Au颗粒的共振吸收峰在500 nm附近。用单光束纵向扫描方法测量了样品的三阶非线性光学效应,使用的光源为调Q的YAG激光器,波长为532 nm,脉宽为10 ns,得到的非线性折射率和非线性吸收系数分别为-2.42×10-6esu和2.22×10-6m/W,表明了Au-BaTiO3复合薄膜有较大的非线性光学响应。     

PLD方法制备的超硬非晶碳薄膜研究

 用脉冲激光沉积在不同条件下制备非晶碳超硬薄膜,研究了非晶碳超硬薄膜的表面形貌、结构、应力、硬度以及能谱等。原子力显微镜和扫描电镜图像显示,薄膜表面平整、致密且光滑,均方根粗糙度最大为0.877 nm。在高激光重复频率、高激光通量条件下,薄膜有很大的应力,致使膜层褶皱甚至破裂,小角X射线衍射表明薄膜为非晶态且最大残余应力达30 GPa以上,但300 ℃温度的原位退火可以有效降低残余应力;纳米压痕测试表明薄膜硬度大于20 GPa,弹性模量大于200 GPa;X射线光电子能谱表明薄膜中sp3的含量在39%~53%之间变化,并且与激光通量成正比。     

PLD方法制备的纳米Fe/Al薄膜的结构及应力分析

 采用PLD方法制备了Fe/Al合金薄膜，研究了Fe/Al合金薄膜的物相、结构、应力等。研究表明薄膜的沉积速率随着衬底温度的升高而降低。原子力显微镜（AFM）图像显示，薄膜表面平整、致密且光滑，均方根粗糙度小于1 nm。等离子体发射谱（ICP）表明Fe/Al原子比为1∶1。X射线小角衍射（XRD）分析表明薄膜中的物相是Al_0.5Fe_0.5，Al_0.5Fe_0.5晶体具有简单立方结构(SC)，晶格常数为0.297 nm，平均晶粒尺寸为81.74 nm，平均微畸变为0.007 6。     

金属纳米团簇复合薄膜Au/BaTiO3与Fe/BaTiO3的PLD制备及其光吸收特征

用脉冲激光沉积技术制备了掺杂纳米金属颗粒Au或Fe的BaTiO₃复合薄膜.用透射电子显微镜和x射线光电子能谱表征了金属颗粒的形态和化学态.330—800nm范围的吸收谱研究表明，掺Au颗粒的BaTiO₃薄膜在580nm附近有一个明显的共振吸收峰，而掺Fe颗粒的BaTiO₃薄膜没有这样的吸收峰.用Mie散射理论对结果进行了分析. 关键词： 复合薄膜 金属颗粒 脉冲激光沉积 吸收谱     

PLD方法制备的纳米Fe/Al薄膜的结构及应力分析

采用PLD方法制备了Fe/Al合金薄膜,研究了Fe/Al合金薄膜的物相、结构、应力等。研究表明薄膜的沉积速率随着衬底温度的升高而降低。原子力显微镜（AFM）图像显示,薄膜表面平整、致密且光滑,均方根粗糙度小于1 nm。等离子体发射谱（ICP）表明Fe/Al原子比为1∶1。X射线小角衍射（XRD）分析表明薄膜中的物相是Al0.5Fe0.5,Al0.5Fe0.5晶体具有简单立方结构(SC),晶格常数为0.297 nm,平均晶粒尺寸为81.74 nm,平均微畸变为0.007 6。     

脉冲激光气相沉积法制备的非晶CH薄膜特性分析

采用脉冲激光气相沉积(PLD)法,研究了氢气压强对非晶CH薄膜性能的影响。原子力显微镜图和白光干涉图显示,薄膜表面平整致密,随着氢气压强增大,粗糙度变大。拉曼光谱分析表明,氢气压强增加,G峰和D峰位置都在向高波数方向移动。傅里叶变换红外光谱分析显示,薄膜中存在sp3—CH2和sp2—CH等基团。最后,采用PLD漂浮法在最优参数氢气压强为0.3 Pa下,成功制备了不同厚度(100~300 nm)、满足一定力学强度、无明显宏观缺陷的自支撑CH薄膜。     

脉冲激光气相沉积法制备的非晶CH薄膜特性分析

采用脉冲激光气相沉积(PLD)法,研究了氢气压强对非晶CH薄膜性能的影响。原子力显微镜图和白光干涉图显示,薄膜表面平整致密,随着氢气压强增大,粗糙度变大。拉曼光谱分析表明,氢气压强增加,G峰和D峰位置都在向高波数方向移动。傅里叶变换红外光谱分析显示,薄膜中存在sp3—CH2和sp2—CH等基团。最后,采用PLD漂浮法在最优参数氢气压强为0.3 Pa下,成功制备了不同厚度（100~300 nm）、满足一定力学强度、无明显宏观缺陷的自支撑CH薄膜。     

On the optical properties of amorphous Ge-Ga-Se-KBr films prepared by pulsed laser deposition

Amorphous thin films (1 − x)(4GeSe₂-Ga₂Se₃)-xKBr (x = 0, 0.1, 0.2, 0.3) were prepared by the pulsed laser deposition (PLD) technique. The optical parameters were calculated using the Swanepoel method from the optical transmission spectra. The optical band gap () of the studied films increased while the index of refraction decreased when increased the content of KBr. The Tauc slopes were discussed as an indicator of the degree of structural randomness of amorphous semiconductors. The index of refraction decreased and increased after annealing of as-deposited films below the glass transition temperature. The thermal-bleaching and thermal- contraction effects were observed, which are discussed in relation to the reduction in the density of homopolar bonds confirmed by the Raman spectra analysis and the decreased amount of fragments of the as-deposited films, respectively.     

Magnetic/non-magnetic nanoparticles films with peculiar properties produced by ultrashort pulsed laser deposition

Films of magnetic nanoparticles uniformly mixed with non-magnetic nanoparticles have been produced by ultrashort pulsed laser deposition. These films present innovative characteristics with respect to their counterparts produced by standard techniques, as for example nanosecond laser ablation or sputtering, due to the peculiar shape and preferential distribution of their constituent nanoparticles. In the present investigation, the difficult coalescence among the deposited nanoparticles, specific characteristic of the ultrashort pulsed laser deposition, is particularly stressed for what concerns its effect on the collective magnetic behaviour. In particular, we observed that, even for a significant fraction of magnetic particles, the films exhibit an unusual high remanent magnetization, together with relatively low values of saturation and coercive fields, showing a strong squareness of the hysteresis loops. In perspective, these nanogranular films appear very promising for potential application as permanent magnets and in magnetic recording.     

Effect of the laser fluence on structural and optical characterization of thin CdS films synthesized by femtosecond pulsed laser deposition

CdS thin films have been grown on Si(1 1 1) and quartz substrates using femtosecond pulsed laser deposition. X-ray diffraction, atomic force microscopy, photoluminescence measurement, and optical transmission spectroscopy were used to characterize the structure and optical properties of the deposited CdS thin films. The influence of the laser fluence (laser incident energy in the range 0.5–1.5 mJ/pulse) on the structural and optical characterizations of CdS thin films has been studied. The results indicate that the structure and optical properties of the CdS thin films can be improved as increasing the per pulse output energy of the femtosecond laser to 1.2 mJ. But when the per pulse output energy of the femtosecond laser is further increased to 1.5 mJ, which leads to the degradation of the structure and optical properties of the CdS thin films.     

Characterization of polymer thin films obtained by pulsed laser deposition

The development of laser techniques for the deposition of polymer and biomaterial thin films on solid surfaces in a controlled manner has attracted great attention during the last few years. Here we report the deposition of thin polymer films, namely Polyepichlorhydrin by pulsed laser deposition. Polyepichlorhydrin polymer was deposited on flat substrate (i.e. silicon) using an NdYAG laser (266 nm, 5 ns pulse duration and 10 Hz repetition rate).The obtained thin films have been characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and spectroscopic ellipsometry.It was found that for laser fluences up to 1.5 J/cm² the chemical structure of the deposited polyepichlorhydrin polymer thin layers resembles to the native polymer, whilst by increasing the laser fluence above 1.5 J/cm² the polyepichlorohydrin films present deviations from the bulk polymer.Morphological investigations (atomic force microscopy and scanning electron microscopy) reveal continuous polyepichlorhydrin thin films for a relatively narrow range of fluences (1-1.5 J/cm²).The wavelength dependence of the refractive index and extinction coefficient was determined by ellipsometry studies which lead to new insights about the material.The obtained results indicate that pulsed laser deposition method is potentially useful for the fabrication of polymer thin films to be used in applications including electronics, microsensor or bioengineering industries.     

Optical models for the ellipsometric characterization of carbon nitride layers prepared by inverse pulsed laser deposition

Amorphous carbon nitride (CN_x) films were prepared by KrF excimer laser ablation of a graphite target in a nitrogen atmosphere in the inverse PLD geometry. From the ellipsometric point of view, the challenging properties of these films were their exponentially decaying thickness as a function of distance from the ablation source, accompanied by a laterally varying chemical composition and structure. Optical models were developed to accurately describe the dependence of film properties on distance from the ablation, layer thickness, and nitrogen pressure. Multi-layer models were used to characterize the surface roughness as well as lateral inhomogeneities. Multiple angles of incidence and multiple wavelengths were applied in the ranges of 66-72° and 250-1000 nm, respectively. A microspot capability of the spectroscopic ellipsometer (with a spot size of about 100 μm) was exploited to decrease the error caused by the lateral inhomogeneity within the measurement spot. Material properties were derived using the empirical Cauchy dispersion model as well as the Tauc-Lorentz parametric dielectric function model. These models allowed the quantitative determination of the band gap and the oscillator parameters in addition to the layer thicknesses and dielectric functions.     

Deposition of zinc oxide thin films by reactive pulsed laser ablation

Thin films of zinc oxide have been deposited by reactive pulsed laser ablation of Zn and ZnO targets in presence of a radio frequency (RF) generated oxygen plasma. The gaseous species have been deposited at several substrate temperatures, using the on-axis configuration, on Si (1 0 0). Thin films have been characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and infrared spectroscopy. A comparison among conventional PLD and reactive RF plasma-assisted PLD has been performed.     

等离子体增强脉冲激光沉积o-BN薄膜

利用等离子体增强脉冲激光沉积系统在Si（100）基底上沉积出了高质量的o-BN薄膜,利用红外光谱（FTIR）、X射线衍射谱（XRD）和原子力显微镜照片对o-BN薄膜进行了表征.通过红外光谱（FTIR）得到o-BN薄膜的红外峰特征峰值为1189cm^-1,1585cm^-1和1450cm^-1;由XRD谱得到o-BN薄膜的（111）,（020）,（021）,（310）和（243）各晶面的衍射峰, 特别是（310）和（243）晶面的衍射峰非常强;通过原子力显微镜照片清楚看到BN薄膜具有尖状突起的表面形貌. 关键词： 等离子体增强脉冲激光沉积 氮化硼薄膜 X射线衍射谱