Effect of iodine on some properties of iodine doped selenium films

The effects of iodine on some properties of iodine-doped selenium films are investigated by X-ray, scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), Raman spectroscopy and X ray photoelectron spectroscopy (X.P.S.)

Informations on the growth, composition, morphology and texture of the films have been obtained

We have shown that the grain size decreases with the increase of the quantity of iodine present in the samples. It is found that iodine is not uniformly distributed in the films and that only a small proportion of iodine in the form of I₃⁻ reacts with the selenium The remaining part probably segregates at the grain boundaries, giving spontaneous sublimation of iodine when the quantity present in the films is of the order greater or equal to 1%.     

Enhanced conductivity in iodine doped polyaniline thin film formed by thermal evaporation

Thermal evaporation technique was employed to deposit pristine and iodine doped polyaniline (PANI) thin films on glass substrates. PANI was synthesized by the chemical oxidation method. Iodine doping was carried out by evaporation. The polymer synthesized was characterized by Thermo Gravimetric Analysis (TGA), Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-VIS) spectroscopy. The evaporation temperature was optimized from TGA measurements. The thin film was deposited in vacuum at 1.33 × 10^− 4 Pa by thermal evaporation of PANI. The polymer film was characterized by FTIR and UV-VIS spectroscopy. The surface morphology of the films was studied by field emission scanning electron microscopy. The resistivity was measured by van der Pauw technique. The conductivity of the doped films was seen to increase with the iodine concentration and many fold increase in conductivity was observed in comparison to the pristine films. The increase in conductivity is due to the generation of polaron band in the band gap upon iodine doping.     

掺杂SnS薄膜的制备及电学性能

硫化锡（SnS）具有很高的光吸收系数和合适的禁带宽度，又无毒性，因此在太阳电池等光电器件中具有潜在应用价值。本文用真空蒸发法制备掺杂的SnS薄膜，掺杂源有Sb、Sb：O3、Se、Te、In、In2O3、Se和In2O3的混合物。对各种掺杂SnS薄膜的厚度、电流-电压（Ⅰ—Ⅴ）特性等进行了表征，并计算了其电阻率和光电导与暗电导的比值（Gphoto／Gdark）。结果表明较有效的掺杂源是Sb，Sb掺杂的薄膜电阻率比纯薄膜的电阻率降低四个数量级，Gphoto／Gdark增加约一倍。同时，研究了Sb掺杂量对SnS薄膜电学性能的影响，表明Sb的最佳掺入量约为1．3wt％～1．5wt％。     

Structural studies on some doped CdS thin films deposited by thermal evaporation

The influence of the Mn, Se and Sb impurities on the structure and morphology of CdS thin films grown on p⁺ Si wafers was studied. The starting powders were mixed in the same molar ratios (0.3%) and deposited in the same conditions by vacuum thermal evaporation. X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and reflectance studies made on thermal treated thin films (573 K, 2 h in air) evidenced that thin films have a hexagonal oriented structure, and that dopants enter into the CdS lattice merely by substitution. The dopant nature influences the thin film thickness and chemical composition. The doped CdS thin films have roughness in nanometer region and a reflectivity lower than 40%. Silicon substrate acts as a template and favors the retention of Mn and scatters the Sb dopants. The CdS:Se thin film is thicker than CdS:Mn and CdS:Sb ones and is a mixture of doped and undoped nanocrystals.     

Growth of selenium thin films

Quantitative measurements of the formation and growth of selenium films on sapphire, glass, aluminium and nickel substrates have been made for various substrate temperatures (T) and evaporation times (t) using a scanning electron microscope (SEM). The film formation and growth process was thought to be a mechanism of the adsorption of impinging selenium atoms on the stable clusters, and the growth of these clusters as evaporation continues. The difference in the values of the activation energies for the growth of selenium on different substrates was explained by considering them as apparent energies which contain the adsorption, desorption, surface diffusion and binding energy terms. The experimental results also indicated an increase in there-evaporation of adatoms from the substrates at higher temperatures.     

掺杂ZnO薄膜研究

采用电子束蒸发方法在玻璃衬底上制备ZnO薄膜和掺杂ZnO薄膜.通过X射线衍射、台阶仪及Hall效应等测试研究了衬底温度和掺杂对晶体质量和电学性能的影响,发现原位生长的ZnO薄沿c轴择优生长,且掺杂ZnO薄膜具有低达3.029×10-4Ω·cm的电阻率.     

Diffusion-limited evaporation of thin polar liquid films

The stability of evaporating very thin films of a polar liquid is investigated. The microscopic interaction with the substrate and capillarity are taken into account in a lubrication equation. The stability of a flat interface is studied when evaporation is limited by the diffusion of the vapour in the gas phase. The evaporation rate is computed and evaporation is shown to be stabilizing. A stability phase diagram is obtained. A weakly nonlinear analysis leads to a film-thickness amplitude equation that is non local in space. Physical consequences of the results are eventually discussed.     

Structural phototransformations in thin selenium films

Light-induced changes in thin amorphous selenium films deposited by pulsed laser evaporation were investigated. Films under 300 nm thick were found to undergo a photocoagulation process in which smooth continuous areas became mottled and discontinuous after exposure for about 10 min to white light at 10 mW cm^-2. Thicker films, if exposed for 10 h or more, formed micron-scale crystallites by a mechanism previously described by Dresner and Stringfellow. The likely mechanism for the photocoagulation process involves the light-induced relaxation of a metastable void-filled short-chain selenium film into a denser equilibrated film which does not readily wet glass or silicon. Both photocoagulation and photocrystallization processes were used to produce patterns on selenium-coated substrates; the effect of varying film thickness and exposure time on the pattern contrast ratio was studied.     

Indium doped silver oxide thin films prepared by reactive electron beam evaporation technique: electrical properties

The indium doped silver oxide thin films have been prepared at 275 °C on soda lime glass and silicon substrates by reactive electron beam evaporation technique; the deposition rate has been varied (by varying the electron beam current) in the range 0.94–16.88 nm/s keeping the oxygen flow rate constant. These films are polycrystalline. The electrical resistivity for these films decreases with increasing deposition rate. The AIO films prepared with a deposition rate of 5.7 nm/s show near p-type conductivity. The work function has been measured on these films by contact potential method using Kelvin Probe. The surface morphology of the films has been evaluated using atomic force microscopy (AFM). The roles of indium doping and oxygen vacancies in the electrical properties of these films have been analyzed; the ionized impurity scattering is the dominant mechanism controlling the electrical conduction in these films.     

Chemical stability of doped ZnO thin films

We present the results of a chemical etching stability study carried out on ZnO thin films doped with several elements deposited by spray pyrolysis. Prior to the etching, a structural study was done by X-ray diffraction and the texture of the samples was obtained by scanning electron microscopy. The samples were etched employing a solution of dilute hydrochloric acid. The etching rates obtained for the different samples depend on the dopant element and our results confirm that films doped with Cr present the highest stability against chemical etching.     

真空热蒸发镀CIAS薄膜

采用真空热蒸发方法在普通玻璃基底上制备Cu In0.7Al0.3Se2(CIAS)薄膜,并对之进行450℃真空硒化退火处理。结果表明,制备的CIAS薄膜具有黄铜矿结构并且以(112)晶面优先生长。真空硒化退火后,薄膜晶体结构更完整,晶粒长大,成分分布均匀,更接近CIAS晶体的化学计量比。薄膜为P型半导体,退火后的薄膜禁带宽度减小至1.38 e V,带电粒子数下降至2.41E+17 cm-3,带电粒子迁移率增加至5.29 cm2/(N·s),电阻率升高至4.9Ω·cm。     

Silica doped with lanthanum sol-gel thin films for corrosion protection

We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol-gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties.     

真空蒸发制备Sb掺杂CdTe薄膜

采用真空蒸发技术在玻璃衬底上制备了Sb掺杂的CdTe薄膜,薄膜为沿(111)晶向择优生长的立方闪锌矿结构的CdTe,结果表明Sb掺杂使得薄膜表面更加均匀致密,改善了薄膜的结晶状况,增大了薄膜的光吸收范围,同时也使薄膜的带隙宽度有所减小,大大降低了薄膜的电阻率.     

Matrix assisted pulsed laser evaporation of biomaterial thin films

In this paper, processing of biomaterial thin films using a novel physical vapor deposition process known as matrix assisted pulsed laser evaporation (MAPLE) is reviewed. The matrix assisted pulsed laser evaporation process provides excellent control over several film parameters, including thickness, roughness, homogeneity, and reliability. Deposition of dexamethasone thin films, poly (d, l) lactic acid/dexamethasone bilayer thin films, and chitosan thin films is reviewed. The results highlight the expanding role of matrix assisted pulsed laser evaporation process in biomaterials, drug delivery, and tissue engineering.     

掺杂氧化钨薄膜的电致变色特性

掺杂氧化钼对氧化钨薄膜的电致变色特性有一定的影响,本文介绍了用电子束蒸发制备不同MoO3掺杂比例的氧化钨膜,对其着色态与漂白态的光学特性以及循环伏安特性进行了实验研究,通过对循环伏安曲线的分析,对杂氧化钨薄膜电致变色的机理进行了讨论。     

Electrical properties of In doped CdS thin films

Indium doped polycrystalline cadmium sulphide CdS:In thin films have been prepared by the spray pyrolysis technique on glass substrates in an enclosed dome. The different scattering mechanisms such as lattice, impurity and grain boundary scattering for CdS:In films are observed at low temperature, in the range of 303 to 120 K. The experimentally determined mobilities due to these scatterings are well interpreted with those of theoretically calculated mobilities. The d.c. conductivity for CdS:In films has also been studied in the same temperature region. The Mott variable range hopping conduction process followed below the temperature of 150 K. The Mott parameters such as N(E _F ), R, W and are found to be 1.26 × 10¹⁹ eV^–1cm^–3, 9.8 × 10^–-7cm, 0.02 eV^–1 and 2.38 × 10⁶cm^–1, respectively from the conductivity data.     

Optical properties of pyrene doped polymer thin films

Thin films of pyrene in polystyrene matrix have been prepared by spin coating technique. The concentration of polystyrene is kept constant to 1 wt.% while that of pyrene dopant varied in the range 2.30×10⁻⁴-2.30×10⁻¹ wt.%. Thickness of the films was found to depend upon concentration of pyrene and varies from 90 to 782 nm. The results of X-ray diffraction analysis reveal the crystalline nature of the films. The optical properties were studied by absorption, excitation and fluorescence spectroscopy. The band gap energy of pyrene in polymer films was calculated from absorption results. A transition from monomer to excimer is observed with thickness variation of the films. The structured part of the spectrum is assigned to the monomer emission while the broad emission band is attributed to well known pyrene excimer-like emission.