Influence of substrate rotation speed on the nanostructure of sculptured Cu thin films

Different rotation speeds of the substrate about its surface normal were used to produce sculptured copper thin films of ∼ 90 nm thickness. X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to obtain nano-structure and morphology of these films. Their optical properties were measured by spectrophotometry in the spectral range of 340-850 nm. Real and imaginary refractive indices, film thickness and fraction of metal inclusion in the film structure were obtained from optical fitting of the spectrophotometer data.     

LPCVD氮化硅薄膜的化学组成

分别采用X光电子能谱(XPS)、俄歇电子能谱(AES)、傅立叶红外光谱(FTIR)以及弹性反冲探测(ERD)等方法,分析了三氯硅烷-氨气-氮气体系低压化学气相沉积(LPCVD)氮化硅(SiNx)薄膜的化学组成,并利用原子力显微镜(AFM)观察了SiNx薄膜的表面形貌.XPS分析结果表明,当原料气中氨气与三氯硅烷的流量之比小于3时获得富Si的SiNx薄膜,当流量之比大于4时获得近化学计量的SiNx薄膜(x=1.33).AES深度分析与XPS分析结果很好地吻合,在835cm-1产生的强红外吸收峰表明Si-N键的形成,ERD分析表明所制备SiNx薄膜中的氢含量很低(1.2at.%).AFM分析结果表明,所沉积的SiNx薄膜均匀、平整,薄膜的均方根粗糙度RMS仅为0.47nm.     

Atomic vapor deposition approach to In2O3 thin films

In2O3 thin films were grown by atomic vapor deposition (AVD) on Si(100) and glass substrates from a tris-guanidinate complex of indium [In(N(i)Pr2guanid)3] under an oxygen atmosphere. The effects of the growth temperature on the structure, morphology and composition of In2O3 films were investigated. X-ray diffraction (XRD) measurements revealed that In2O3 films deposited in the temperature range 450-700 degreesC crystallised in the cubic phase. The film morphology, studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM), was strongly dependent on the substrate temperature. Stoichiometric In2O3 films were formed under optimised processing conditions as was confirmed by X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), as well as by Rutherford backscattering spectrometry (RBS). Finally, optical properties were investigated by photoluminescence (PL) measurements, spectroscopic ellipsometry (SE) and optical absorption. In2O3 films grown on glass exhibited excellent transparency (approximately 90%) in the Visible (Vis) spectral region.     

Characterization on pulsed laser deposited nanocrystalline ZnO thin films

Nanocrystalline zinc oxide thin films were deposited on glass and silicon substrates by using pulsed laser deposition at different laser energy densities (1.5, 2, and 3 J/cm²). The film thickness, surface roughness, composition, optical and structural properties of the deposited films were studied using an α-step surface profilometer, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), optical transmittance, and X-ray diffraction (XRD), respectively. The film thickness was calculated as 244 nm. AFM analysis shows that the root-mean-square roughness increases with increasing laser energy density. XPS analysis shows that the interaction of zinc with oxygen atoms is greatly increased at high laser energy density. In the optical transmittance spectra, a shift of the absorption edge towards higher wavelength region confirms that the optical band gap increases with an increase in laser energy density. The particle size of the deposited films was measured by XRD, it is found to be in the range from 7.87 to 11.81 nm. It reveals that the particle size increases with an increase in laser energy density.     

Surface blistering of low temperature annealed hydrogen and helium co-implanted germanium and its application to splitting of bonded wafer substrates

Applications involving transfer of germanium layers to silicon-based substrates often require a process involving a restricted thermal budget. The use of relatively low temperatures has a major advantage in reducing stresses when thermal splitting of implanted germanium wafers bonded to silicon-based substrates is used to create germanium-on-oxide (GeOI) layers. The present study investigates the phenomenon of blistering of hydrogen and helium co-implanted germanium over the temperature range 250–400 °C, optical microscopy being used to detect the initial appearance of the blisters. Results showed that plots of Ln(time) vs. blister initiation temperature consisted of several straight-line regions yielding an activation energy for each region. The plots showed similarities to those observed in previous work with silicon co-implanted and annealed under similar conditions. At temperatures below the blister initiation temperature, transmission electron microscopy (TEM), revealed the presence of spherical bubbles at a depth below the surface estimated to be approximately that of the hydrogen implant projected range. GeOI layers were produced by thermal splitting of co-implanted germanium wafers bonded to oxide-coated silicon substrates wafers at a temperature of 300 °C. The RMS roughness of the split germanium surface measured by atomic force microscopy (AFM) was about 11 nm averaged over the wafer surface. In addition there were isolated and randomly distributed regions of 27 nm roughness covering about 20% of the total surface area of the wafer.     

Optical study on II-VI semiconductor nanoparticles in Langmuir-Blodgett films

Cadmium sulfide (CdS) nanoparticles formed within Langmuir-Blodgett (LB) films of stearic acid and calix[8]arene were studied with different optical methods including surface plasmon resonance (SPR), ellipsometry and UV-visible absorption and fluorescence spectroscopies. For the first time, the process of formation of CdS nanoparticles within LB films was monitored in-situ with SPR. The results of ellipsometry, SPR and UV-vis absorption spectroscopy were analyzed to evaluate simultaneously the thickness, refractive index and extinction coefficient of LB films. It was shown that all three parameters increase as a result of formation of CdS nanoparticles. Photoluminescence measurements provided direct confirmation directly for previous observation with UV-vis absorption spectroscopy of the blue spectral shift caused by CdS particles formation. The observed large Stoke's shift of the luminescence band is discussed in terms of the formation of "dark excitons" in the platelet-type CdS nanoclusters. AFM study shows the formation of pseudo-two dimensional platelets of CdS with the lateral dimensions in the range of 20-30 nm.     

TiB2超硬薄膜的合成及性能

采用离子束溅射方法制备了ＴｉＢ２硬质薄膜，ＡＦＭ观察表明薄膜表面非常光谱，ＡＥＳ、ＸＲＤ和ＸＰＳ分析证明薄膜中主要是Ｂ、Ｔｉ比为１．８，六方结构的ＴｉＢ２多晶体、且呈现强烈的（１０１）择优取向，由超显微压痕测量系统测得的加载、卸载曲线计算得到的薄膜的显微硬度比高达４８ＧＰａ     

Structural transition of ZnO thin films produced by RF magnetron sputtering at low temperatures

Zinc oxide (ZnO) thin films were prepared using reactive radio-frequency magnetron sputtering of a pure metallic zinc target onto glass substrates. The evolution of the surface morphology and the optical properties of the films were studied as a function of the substrate temperature, which was varied from 50 to 250 °C. The surface topography of the samples was examined using atomic force microscopy (AFM), and their optical properties were studied via transmittance measurements in the UV–Vis–NIR region. DRX and AFM analyses showed that the surface morphology undergoes a structural transition at substrate temperatures of around 150 °C. Actually, at 50 °C the formation of small grains was observed while at 250 °C the grains observed were larger and had more irregular shapes. The optical gap remained constant at ~3.3 eV for all films. In the visible region, the average optical transmittance was 80 %. From these results, one can conclude that the morphological properties of the ZnO thin films were more greatly affected by the substrate temperature, due to mis-orientation of polycrystalline grains, than were the optical properties.     

Ge:Si:O evaporated alloys as a thermosensitive layer for large area bolometers

A study of the composition and properties of amorphous Ge:Si:O thin films deposited at low temperature by reactive coevaporation is presented. Films with various compositions are obtained by separately controlling the evaporation rates of germanium and silicon. The composition of films is measured by combining Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA) and energy dispersive X-ray analysis (EDX) techniques. Films are characterized by FTIR absorption spectroscopy, VIS-NIR transmittance and temperature behaviour of the electrical resistivity. The analysis of all experimental data shows that oxygen incorporation depends on the silicon content in the films. Oxygen atoms appear mainly bonded to silicon and not to germanium. An uniformed distribution rather than a cluster structure of silicon oxide into a germanium matrix is suggested. Both optical band gap energy and thermal coefficient of the resistivity vary with composition of films. Preliminary studies of thin films with similar composition obtained using reactive sputtering from a composite target evince the coexistence of SiO and GeO bonds.     

Spray deposition and characterization of nanostructured Li doped NiO thin films for application in dye-sensitized solar cells

Transparent conducting Li (0-5?wt%) doped NiO thin films with preferential growth along the (111) plane were deposited onto glass substrates by pyrolytic decomposition of nickel nitrate and lithium chloride precursors at 500?°C in air. The effect of Li concentration on the structural, optical and transport properties of NiO thin films was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectral transmittance, photoluminescence and linear four-probe resistivity. Activation energies as a function of Li concentration were deduced from the temperature dependent resistivity data measured in the range 300-448?K. The figure of merit was deduced by combining the spectral transmittance and sheet resistance values. The variation in properties of NiO thin film due to Li doping are discussed based on the above results. A dye-sensitized solar cell has also been fabricated for the optimized Li doped NiO thin film and the results are presented.     

Thin-film polarizers for visible spectral range with nanostructured surface modified by carbon nanotubes

The effect of carbon nanotubes (CNTs) on the optical and mechanical properties of iodinated poly(vinyl alcohol) (PVA) polarization films for the visible spectral range is briefly considered. The application of CNTs onto iodinated PVA films increases their optical transmission in the 200–750 nm wavelength range and produces their surface hardening.     

A microstructural study on the surface and interface of CdTe/CdS solar cells

The surface and interface properties of CdTe/CdS solar cells, including interfacial mixing, surface and interface geometrical morphology, CdTe grain size and preferential crystal orientation of CdTe layers were studied using Auger electron spectroscopy (AES) depth profiling, atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, optical reflectance (OR) and X-ray diffraction (XRD) techniques. The correlation between the surface and interface properties and CdTe/CdS solar cell performance was also investigated. AES depth profiling was used to analyse the interdiffusion between the CdTe and CdS layers. Atomic force microscopy (AFM) suggests that the interfacial geometrical morphology has a significant influence on the photovoltaic property of CdTe/CdS solar cells. Rough interfaces tend to increase the photovoltaic conversion efficiency of solar cells because of multiple reflections. X-ray diffraction shows that polycrystalline CdTe/CdS solar cells with higher efficiencies appear to be orientated with more (1 1 1) planes of CdTe parallel to the macrosurface, but CdTe single crystals with differently indexed surface planes show almost the same reflection behaviour. Further theoretical and experimental analyses are therefore needed to clarify this observation. This revised version was published online in July 2006 with corrections to the Cover Date.     

空间防静电薄膜的制备及耐辐照性能研究

利用射频磁控溅射工艺制备了ITO防静电薄膜。研究了辐照试验前后ITO样品的光电性能变化,并用XPS和AFM对其组分及表面形貌变化进行了分析。结果表明,辐照后ITO薄膜的光学透过率变化不大;表面电阻有一定增加,但幅度不大,完全可以满足防静电的要求。     

Effect of Al dopants on the structural,optical and gas sensing properties of spray-deposited ZnO thin films

Undoped and Al-doped ZnO thin films were deposited on glass substrates by the spray pyrolysis method. The structural, morphological and optical properties of these films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–Vis spectroscopy, photoluminescence (PL) and photoconductivity (PC) measurements, respectively. XRD analyses confirm that the films are polycrystalline zinc oxide with the hexagonal wurtzite structure, and the crystallite size has been found to be in the range 20–40 nm. SEM and AFM analyses reveal that the films have continuous surface without visible holes or faulty zones, and the surface roughness decreases on Al doping. The Al-doped films have been found to be highly transparent (>85%) and show normal dispersion behavior in the wavelength range 450–700 nm. The doped films show only ultraviolet emission and are found to be highly photosensitive. Among all the films examined, at 300 °C the 1.0 at% Al-doped film shows the selective high response (98.2%) to 100 ppm acetone concentration over to methanol, ethanol, propan-2-ol, formaldehyde and hydrogen.     

Structural, photoluminescence and optical properties of chemically deposited (Cd1−xBix)S thin films as a function of dopant concentration

In this study, (Cd_1?xBi_x)S thin films were successfully deposited on suitably cleaned glass substrate at 60 °C temperature, using the chemical bath deposition technique. After deposition, the films were also annealed at 400 °C for 2 min in air. The structural properties of the deposited films were characterized using X-ray diffraction and AFM. Formation of cubic structure with preferential orientation along the (111) plane was confirmed together with BiS second phase from structural analysis. The interplanar spacing, lattice constant, and crystallite size of (Cd_1?xBi_x)S thin films were calculated by the XRD. The crystallite size of the un-doped CdS thin films was found to be 7.84 nm, which increased to 11.1 nm with increasing Bi content from 0 to 10 %. The surface roughness of the films was measured by AFM studies. The photoluminescence spectra were observed at red shifted band edge peak with increasing doping concentration of Bi from 0 to 5 % in the un-doped CdS thin films. The optical properties of the films are estimated using optical absorption and transmission spectra in the range of 400–800 nm using UV–VIS spectrophotometer. The optical band gap energy of the films was found to be decreased from 2.44 to 2.23 eV with the Bi content being from 0 to 5 %. After annealing, the band gap of these films further decreased.     

Surface properties of thin-film polarizers modified by carbon nanostructures

The influence of laser-deposited single- and multiwalled carbon nanotubes (CNTs) on the optical and mechanical properties of iodinated poly(vinyl alcohol) (PVA) polarization films for the visible spectral range is considered. A possible mechanism of the CNT-induced modification of the surface and spectral properties of iodinated PVA films is proposed.     

纳米二氧化钛表面组成及其微结构分析技术进展

介绍了纳米TiO2表面组成，微结构分析技术近年来的进展，光电子能谱技术包抱X光电子能谱（XPS）和俄歇光电子能谱（AES），光谱分析技术包括红外光谱（IR）和Raman光谱，显微分析技术中有扫描隧道显微镜（STM），原子动力显微镜（AFM）及扫描和透射电子显微镜（SEM，TEM），X射线分析技术主要是X射线衍射（XRD）。     

Effect of calcination and pH value on the structural and optical properties of titanium oxide thin films

Titanium oxide thin films on glass and silicon wafer substrates were prepared by the sol-gel process. The pH variation and the calcination effect on the optical and structural properties of the films were systematically examined. The coated films were characterized by atomic-force microscopy (AFM), NKD analyzer, X-ray diffraction (XRD) and cyclic voltammograms (CV). The influence of calcination and pH value on the spectra of transmittance, reflectance, and refractive indices and on the surface structure has been investigated. From X-ray diffractometric measurements (XRD), it has been confirmed that the films are an anatase form. The effects of pH and surface modification of titanium oxide were studied with AFM images. These showed that the surface texture was changed dramatically according to calcinations and pH variation. Spectral dependencies of refractive indices (n) were determined for all films. Band-gap energy (E_g) was also estimated for these films.     

The electromagnetic interference shielding effect of indium-zinc oxide/silver alloy multilayered thin films

A study was made to examine the electromagnetic interference (EMI) shielding effect of multilayered thin films in which indium-zinc oxide (IZO) thin films and Ag or Ag alloy thin films were deposited alternately at room temperature using a RF magnetron sputtering. The optical, electrical and morphological properties of the constituent layers were analyzed using an ultraviolet-visible photospectrometer, a 4-point probe and an atomic force microscopy (AFM), respectively. The EMI shielding effect of the multilayered thin films was also measured using a coaxial transmission line method. A detailed analysis showed that the control of the film morphologies, i.e., the surface roughnesses of the constituent metal layers was essential to an accurate estimate of the electrical and optical properties of multilayered coatings. It was shown that properly designed IZO/Ag alloy multilayered thin films could yield a visible transmission of more than 70%, a sheet resistance of less than 1 Ω/sq., together with an EMI shielding effect larger than 45 dB in the range from 30 to 1000 MHz.     

Optical and structural characterization of silver islands films on glass substrates

Metal island films (MIFs) of Ag on glass substrates were fabricated by the e-beam evaporation technique. The dependence of the surface plasmon (SP) absorption properties on the deposition mass thickness and substrate temperature was quantified. The structural and optical characterization of the MIFs, obtained using spectrometry, grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscopy (AFM) evidences the evolution of SP characteristics depending on the fabrication parameters: the red shift of the absorption peaks with the increase of deposition thickness accompanied by peak widening and the blue-shift of peaks with the increase of deposition temperature followed by the peak narrowing. These findings were explained by the differences in the concentration, shape and size of the obtained silver islands.