Characterization of the bonding structure of nanocrystalline diamond and amorphous carbon films prepared by plasma assisted techniques

Thin nanocrystalline diamond/amorphous carbon (NCD/a-C) composite films and amorphous diamond-like carbon (DLC) films were prepared by three methods: microwave plasma chemical vapour deposition (MWCVD) from methane/nitrogen mixtures (NCD/a-C), RF magnetron sputtering of a pure graphite target in argon/methane ambients, and pulsed laser deposition (PLD) in vacuum or argon atmosphere (DLC). The films prepared by the three techniques were comprehensively characterized with respect to their bonding structure by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). PACS 81.05.Uw; 82.80.Pv     

Surface composition and electronic properties of indium tin oxide and oxynitride films

The surface properties of indium tin oxynitride films prepared by rf-sputtering in nitrogen atmosphere were investigated by X-ray and ultraviolet photoelectron spectroscopy as well as electron energy loss spectroscopy and Auger electron spectroscopy depth profiling. The results are compared to reference measurements on conventional rf-sputtered indium tin oxide films. The incorporated nitrogen is present in different chemical environments. Employing these different spectroscopic techniques, it was found that desorption of nitrogen from the ITON structure upon annealing is the origin of the observed drastical changes in the surface composition and electronic structure. The formation of oxygen vacancies and Sn surface segregation upon annealing is linked to improvements in the physical properties (larger spectral range of transmittance and higher conductivity) of the films.     

Growth of GaN films on CoGa(001): an EELS and AES study

The formation and properties of ultra-thin GaN films were investigated by means of high-resolution electron energy-loss spectroscopy (EELS) and Auger electron spectroscopy (AES). Using the intermetallic alloy CoGa as the substrate material, GaN can be prepared on the (001) surface upon adsorption of ammonia at 80 K and subsequent thermal decomposition. Ultra-thin GaN films were grown by repeated cycles of ammonia adsorption and heating to 650 K. The GaN films show an FK mode at 695 cm⁻¹, in agreement with calculated spectra based on IR parameters. The electronic energy gap is determined to be E_g ≈ 3.5 eV.     

乙醇对纳米多孔氧化铝薄膜光致发光特性的影响

采用二次阳极氧化法,用乙醇与草酸的混合溶液制备纳米多孔氧化铝薄膜。扫描电子微镜结果显示,乙醇与草酸混合溶液中制备的氧化铝薄膜形貌更规整,有序度更高。光致发光测试结果表明,该混合电解液制备的薄膜的光致发光强度有明显的提高,且随乙醇浓度的增加,发光强度逐渐增大。结合红外反射光谱及X光电子能谱对上述实验现象进行了分析,为多孔氧化铝薄膜掺杂和改善其发光特性提供了新的思路。     

Protection of iron against corrosion by coverage with Au nanoparticles and n-hexylthiol mixed films

Through a one-step thermal reaction, Au nanoparticles were synthesized and self-assembled mixed films of Au nanoparticles and n-hexylthiol were prepared on iron surface. The size distribution and shape of Au nanoparticles were examined using transmission electron microscopy (TEM). Results of two electrochemical methods - electrochemical impedance spectroscopy (EIS) and polarization curves indicate that self-assembled mixed films can form on the iron surface and prevent it from corrosion effectively. Energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) measurements were applied to identify the formation of the mixed films on iron surface.     

Raman characterization of the structural evolution in amorphous and partially nanocrystalline hydrogenated silicon thin films prepared by PECVD

Hydrogenated silicon (Si:H) thin films were obtained by plasma‐enhanced chemical vapor deposition (PECVD). Raman spectroscopy was used to investigate the structural evolution in phosphor‐doped n‐type amorphous hydrogenated silicon thin films, which were prepared under different substrate temperatures and gas pressures. Meanwhile, the effect of nitrogen doping on the structure of P‐doped thin films was also investigated by Raman spectroscopy. Moreover, the transition from the amorphous state to the nanocrystalline state of undoped Si:H films deposited through low argon dilution was studied by Raman spectroscopy, X‐ray diffraction, and transmission electron microscopy. The results show that Raman spectroscopy can sensitively detect the structural evolution in hydrogenated silicon thin films deposited under different conditions in a PECVD system. Copyright © 2010 John Wiley & Sons, Ltd.     

化学水浴法和磁控溅射法制备硫化镉薄膜的性能研究

以氯化铵、氯化镉、氢氧化钾和硫脲为反应物采用化学水浴法制备了硫化镉薄膜,为了作对比研究,采用射频磁控溅射以硫化镉为靶材,氩气为溅射气体,制备了硫化镉薄膜。采用X射线衍射、扫描电子显微镜和紫外-可见光光谱仪分别表征了硫化镉薄膜的结构、形貌和光学吸收特性。结果表明,采用以上两种方法制备的硫化镉均具有(002)择优取向,溅射法制备的硫化镉薄膜较致密,薄膜表面较光滑,平均晶粒尺寸在20～30nm;水浴法制备的硫化镉薄膜颗粒尺寸较小,缺陷较多。除了在短波段溅射所得硫化镉薄膜的透过率略差于水浴法所得硫化镉薄膜之外,溅射法制备的硫化镉薄膜的性能整体上优于水浴法制备的薄膜。两种方法制备的硫化镉薄膜的能隙在2.3～2.5eV。     

溶液pH值对化学浴法制备的Cd_xZn_(1-x)S薄膜光电性能的影响

采用氯化镉、氯化锌、硫脲、柠檬酸钠和氨水的溶液体系通过化学浴沉积法合成Cd_xZn_(1-x)S薄膜,利用X射线衍射分析、扫描电子显微镜、能谱仪和紫外可见近红外分光光度计等表征手段研究了Cd_xZn_(1-x)S薄膜的形貌、相结构和光学性能,测试了薄膜的光电流响应曲线并对薄膜的光电性能进行了分析.结果表明:在pH值为10至13范围内成功制备了均匀的Cd_xZn_(1-x)S薄膜;随着pH值升高,薄膜中Zn原子比例与光学带隙减小;制备的薄膜均表现出明显的光电导现象.pH值为11和12时薄膜的表面最为平整致密,结晶性最好,光学带隙分别为2.92eV和2.72eV,光暗电导比均为1.20,光源关闭后电流下降过程最快,10s后电流分别下降了约68.55%和69.39%.     

High resolution electron energy loss spectroscopy surface studies of hydrogenated detonation nano-diamond spray-deposited films

Nano-diamond films composed of 3–5 nm grains prepared by the detonation method and spray deposited onto silicon substrates were examined by high resolution electron energy loss spectroscopy (HR-EELS), Raman spectroscopy and transmission electron microscopy. The HR-EEL spectrum of the annealed and hydrogenated films displays dominant C–H losses at 360–365 meV; the diamond optical phonon and its overtones. These results suggest that the films reveal well defined hydrogenated diamond surfaces on the nanometric scale. Detailed analysis of the diamond optical phonon overtone revealed a red-shift of the basic C–C vibration by 5 meV. We attribute this shift to a phonon quantum confinement effect detected by HR-EELS spectroscopy.     

Effects of electron irradiation on the properties of GZO films deposited with RF magnetron sputtering

Transparent conductive GZO films were deposited on polycarbonate substrates by electron beam assisted radio frequency (RF) magnetron sputtering and then the influence of electron irradiation on the structural, optical and electrical properties of GZO films was investigated by using X-ray diffractometry, UV-vis spectrophotometry, four point probes, atomic force microscopy and UV photoelectron spectroscopy. Sputtering power was kept constant at 3 W/cm² during deposition, while electron irradiation energy varied from 450 to 900 eV.Electron irradiated GZO films show larger grain sizes than those of films prepared without electron irradiation, and films irradiated at 900 eV show higher optical transmittance in the visible wavelength region and lower sheet resistance (120 Ω/□) than other films. The work-function is also increased with electron irradiation energy. The highest work-function of 4.4 eV was observed in films that were electron irradiated at 900 eV.     

Compositional and structural evolution of the titanium dioxide formation by thermal oxidation

Titanium oxide films were prepared by annealing DC magnetron sputtered titanium films in an oxygen ambient. X-ray diffraction （XRD）, Auger electron spectroscopy （AES） sputter profiling, MCs^＋-mode secondary ion mass spectrometry （MCs^＋-SIMS） and atomic force microscopy （AFM） were employed, respectively, for the structural, com- positional and morphological characterization of the obtained films. For temperatures below 875 K, titanium films could not be fully oxidized within one hour. Above that temperature, the completely oxidized films were found to be rutile in structure. Detailed studies on the oxidation process at 925K were carried out for the understanding of the underlying mechanism of titanium dioxide （TiO2） formation by thermal oxidation. It was demonstrated that the formation of crystalline TiO2 could be divided into a short oxidation stage, followed by crystal forming stage. Relevance of this recognition was further discussed.     

图谱分析退火对CdTe多晶薄膜性能影响

对近空间蒸发系统制备的同一CdTe薄膜进行分割并在不同条件下进行退火,通过XRD、SEM、电导温度关系以及XPS等研究退火后薄膜结构,各元素含量分布以及价态变化。结果表明：刚沉积的CdTe薄膜呈立方相,沿(111)明显的择优取向,退火后(111)(220)(311)等峰的强度有不同程度的增强。晶粒长大,晶界减小,降低通过晶界载流子复合概率,降低暗电导激活能,改善电池的并联电阻和漏电流。XPS测试表明样品中存在碲的氧化物,而且随着刻蚀深度的增加氧化物明显减少。通过分析,认为样品中可能存在TeClO₂的结构单元,导致薄膜性能的改变。样品表面氧元素含量较多,随着刻蚀深度的增加,氯氧2种元素的含量明显减少,而且氯元素在样品中达到了稳定的分布。     

电沉积Cu(In,Ga)Se_2预置层硫化退火制备Cu(In,Ga)(Se,S)_2薄膜及表征

在550℃下的H2S气氛中退火处理电沉积制备的Cu(In,Ga)Se2(CIGS)预置层,制备了太阳电池光吸收层Cu(In,Ga)(Se,S)2(CIGSS)薄膜.采用X射线能量色散谱、俄歇电子能谱、扫描电镜、X射线衍射和拉曼光谱对退火前后的薄膜进行表征.结果表明,H2S气氛下退火能够实现薄膜中O的去除和S的掺入,同时使得各元素的纵向分布更加均匀并可消除Cu-Se微相.此外,H2S退火还可改善薄膜的结晶性能,并使S和Ga进入黄铜矿结构,薄膜晶格参数变小.     

Nanoparticulate cerium dioxide and cerium dioxide-titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition

Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)—nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV-visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO₂ nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.     

Optical and structural properties of pulsed laser ablation deposited ZnO thin film

A limited number of reports exists in the literature concerning the systematic study of the structural and optical properties of ZnO thin films, produced by pulsed laser ablation, in correlation with the deposition parameters adopted. In this paper we present a characterization of a sample prepared by this technique and studied by photoelectron spectroscopy and X-ray diffraction. The dielectric function of both target and films has been deduced by reflection electron energy loss spectroscopy.     

不同环境中X射线激光Yb靶表面氧化研究

 用电子束蒸发方法淀积制备X射线激光稀土元素Yb薄膜靶,将薄膜靶在不同的环境气氛中进行氧化。用X射线光电子谱(XPS)、俄歇电子谱(AES)和X射线衍射(XRD)方法研究了Yb薄膜靶表面氧化层的元素价态、组分和微观结构。发现薄膜表面氧化层中存在分层结构,干燥空气中储存的Yb薄膜表面氧化层由表及里的组分依次为化学吸附水、氢氧化物、氧化物及金属元素。表面氢氧化物和氧化物以非晶态形式存在。潮湿空气中水分是薄膜靶氧化速率增加的主要原因。     

Reactive sputter deposition and metal–semiconductor transition of FeS films

FeS polycrystalline films were prepared on float glass by radio-frequency reactive sputtering. X-ray diffraction, scanning electron microscopy, Rutherford backscattering, and secondary ion mass spectroscopy were used to characterize the films. The effects of the deposition parameters, such as sputter power and substrate temperature, on the morphological structure and on the metal–semiconductor phase transition of FeS films were investigated. It has been found that the films show a substrate temperature dependent preferential orientation and phase-transition temperature. PACS 81.15.Cd; 68.55.Jk     

Preparation and Thermal Characterization of Diamond-Like Carbon Films

Diamond-like carbon （DLC） films are prepared on silicon substrates by microwave electron cyclotron resonance plasma enhanced chemical vapor deposition. Raman spectroscopy indicates that the films have an amorphous structure and typical characteristics. The topographies of the films are presented by AFM images. Effective thermal conductivities of the films are measured using a nanosecond pulsed photothermal reflectance method. The results show that thermal conductivity is dominated by the microstructure of the films.     

埋藏于有机介质中金属原子团的结构研究(I)

利用双源同时蒸发和U型管热壁蒸发法制备了两种金属-有机复合薄膜Ag-7,7,8,8-tetracyanoquinodimethane和Ag-1,4-bis-(1,1-dicyanovinyl)-benze.利用透射电子显微镜和可见—紫外光谱研究了所制备的金属-有机复合薄膜的结构特性，发现它们是一种金属原子团埋藏于具有π-共轭体系的有机介质中的薄膜体系. 关键词：     

Influence of silver doping on the photocatalytic activity of titania films

By means of X-ray diffraction, BET nitrogen adsorption, UV-Vis-NIR transmission spectroscopy, transmission electron microscope, scanning electron microscope, X-ray photoelectron spectroscopy and photodegradation of methylene blue, effects of Ag doping on the microstructure and photocatalytic activity of TiO₂ films prepared by sol–gel method were studied. It is found that with a suitable amount (2–4 mol%), the Ag dopant increases the photocatalytic activity of TiO₂ films. The mechanism can be attributed to that (1) anatase grain sizes decrease with Ag doping and the specific surface areas of doped TiO₂ films increase, the charge transfer in TiO₂ films is promoted; (2) by enhancing the electron–hole pairs separation and inhibiting their recombination, the Ag dopant enhances the charge pair separation efficiency for doped TiO₂ films.