Influences of Interface States on Resistive Switching Properties of TiOx with Different Electrodes

Different TiOx thin films prepared by graded or sufficient oxidization of Ti are applied with Pt or Ag electrode in metal？insulator-metal （MIM） structures for studying the properties and mechanisms of resistive switching. The differences on the mobile oxygen vacancies in TiOx films and different work functions of the electrode films result in different insulator-metal interface states, which are displayed as ohmic-like or non-ohmic contact. Based on the interface states, the electrical models for MIM devices are analyzed and extracted. The electrode-limited effect and the bulk-limited effect can be unified to explain the mechanisms for resistive switching behavior as the dominant effect respectively in various conditions. All the current-voltage curves of the four kinds of specimens measured in the experiments can be explained and proved in accordance with the theory.     

Laser Damage Mechanisms of Amorphous Ta2O5 Films at 1064, 532 and 355nm in One-on-One Regime

Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy （AFM） and x-ray photoelectron spectroscopy （XPS）. The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold （LIDT） is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation （I（λ）=aλm）, which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.     

Effect of Different Substrate Temperature on Sb-Doped ZnO Thin Films Prepared by Pulsed Laser Deposition on Sapphire Substrates

Sb-doped ZnO thin films are deposited on c-plane sapphire substrates by pulsed laser deposition. Hall results indicate that the conductivity of the Sb-doped ZnO thin films is strongly dependent on the substrate temperature. The sample deposited at the temperature of 550°C exhibits p-type conductivity. It gives a resistivity of 15.25Ω＆#12539;cm, with a Hall mobility of 1.79cm2V-1s-1 and a carrier concentration of 2.290×1017cm-3 at room temperature. The x-ray diffraction indicates that the Sb-doped ZnO thin films deposited in the range of 450-650°C are high c-axis oriented. Low-temperature photoluminescence spectra indicate that the sample deposited at 550°C shows the strong acceptor-bound exciton （A0X） emission.     

Effects of Rapid Thermal Processing on Microstructure and Optical Properties of As-Deposited Ag2O Films by Direct-Current Reactive Magnetron Sputtering

（111） preferentially oriented Ag2O film deposited by direct current reactive magnetron sputtering is annealed by rapid thermal processing at different annealing temperatures for 5 min. The film microstructure and optical properties are then characterized by x-ray diffractometry, scanning electron microscopy, and spectrophotometry, respectively. The results indicate that no clear Ag diffraction peak is discernable in the Ag2O film annealed below 200°C. In comparison, the Ag2O film annealed at 200°C begins to exhibit characteristic Ag diffraction peaks, and in particular the Ag2O film annealed at 250°C can demonstrate enhanced Ag diffraction peaks. This implies that the threshold of the thermal decomposition reaction to produce Ag particles is approximately 200°C for the Ag2O film. In addition, an evolution of the film surface morphology from compact and pyramid-like to a rough and porous structure clearly occurred with increasing annealing temperature. The porous structure might be attributable to the escape of the oxygen produced during annealing, while the rough surface might originate from the reconstruction of the surface. The dispersion of interference peak intensity in the reflectance and transmission spectra could be attributed to the Ag particles produced. The lowered crystallinity and Ag particles produced induce a lattice defect, which results in an enhanced transmissivity in the violet region and a weakened transmissivity in the infrared region.     

Effect of Annealing on Microstructure and Electrical Characteristics of Doped Poly （3-Hexylthiophene） Films

The effect of annealing on the microstructure and electrical characteristics of poly （3-hexylthiophene） （P3HT） films doped with very small amounts of the electron acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane （F4-TCNQ） is studied. X-ray diffraction and UV-vis spectrum studies show that unlike the pure P3HT film, the thermal treatment on the doped fihns under an Ar atmosphere can effectively enhance the crystalline order of P3HT films, as well as successfully facilitate the orientation of the polymer chains. This improvement is attributed to the electrostatic force between P3HT and F4-TCNQ molecules. This force induces the polymer chains to crystallize and orient during the annealing process. As a result, annealing significantly improves performance, especially for the Ion/Ioff ratio of the TFTs based on the doped P3HT films.     

铁磁/反铁磁双层薄膜自旋波共振谱

本文在一维海森堡模型的基础上,采用界面参数化方法,研究了铁磁/反铁磁双层薄膜中自旋波低温激发问题．重点讨论了表面各向异性对薄膜中自旋波共振谱的影响．结果表明：体系中的自旋波本征模存在共振行为,表面各向异性场对体模、完全禁闭模的共振谱影响较大,对界面模没有影响．     

2-氨基苯硫酚NIR-SERS光谱及其在纳米银表面吸附行为分析

本文采用静电自组装的方法制备了二维纳米银膜。UV-vis吸收光谱显示其等离子体共振吸收带位于400+900nm的光谱范围,延伸到了近红外区,可以较好的匹配785nm的近红外激发光源。以该纳米银膜为基底,对2-氨基苯硫酚(2-ATP)分子进行了近红外表面增强拉曼散射(NIR-SERS)检测,获得了重复性良好的NIR-SERS光谱图。实验表明:以2-ATP为探针分子时,该纳米银膜的NIR-SERS增强因子达到2.19×109。同时,本文采用密度泛函理论(DFT),以B3LYP/6-31G为基函数,对2-ATP分子进行结构优化和普通拉曼光谱(NR)计算,发现理论值和实验值吻合较好。此外,对2-ATP的NIR-SERS谱带进行了归属分析,发现当2-ATP分子在纳米银表面吸附时,是以-SH基团吸附到银表面,且同时-SH基团会被纳米银氧化。     

金属诱导低温制备多晶硅薄膜工艺新进展

多晶硅薄膜由于兼具稳定性、高光敏性、便于大面积沉积等优势成为目前光伏领域的研究热点.本文综述了近几年金属诱导非晶硅薄膜晶化的新工艺,介绍了各种工艺条件对多晶硅薄膜材料的结构、金属含量的调控规律.最后展望了未来的发展趋势.     

染料敏化太阳电池的实验室制备

根据染料敏化太阳电池的工作原理和结构构成,介绍了在基础实验条件下制备染料敏化太阳电池的方法.实验表明,采用天然染料敏化的TiO2半导体薄膜作为光阳极,镀碳的导电玻璃作为反电极,并选用含碘的氧化-还原电解质,通过组装能够产生一定的电能.