IR sensitization of PbSnSe films by heat treatment in air

This paper examines the IR sensitization of Pb_0.975Sn_0.025Se films by heat treatment in air. The films were annealed in the temperature range from 403 to 723 K. Heat treatment was accompanied by the recrystallization of agglomerates in the films. The photosensitivity of the films was shown to depend on heat treatment temperature. The films sensitized in the temperature range 653–700 K offer the highest photosensitivity (80–140 μV). The observed increase in the dark resistance and voltage sensitivity of the films is probably due to the formation of oxide phases on the surface of their microcrystallites.     

CdS纳米晶薄膜的制备及光电性能研究

利用化学浴沉积法,以N(CH2CH2OH)3为络合剂,Cd(CH3COO)2·2H2O和(NH2)2CS为前驱体溶液制备了CdS纳米晶薄膜,利用FESEM、XRD考察了前驱体浓度、络合剂浓度、前驱体溶液的pH值、反应温度等因素对CdS纳米晶薄膜的表面形貌、晶粒大小及晶体结构的影响,在最佳工艺条件下可以制得表面平整,结构致密的CdS纳米晶薄膜。UV-Vis光谱表明CdS在短波长区域有较强的吸收,符合作为窗口材料和过渡层的要求;光电性能测试表明CdS具有较好的光电响应,呈特征n型半导体特性。     

氧化锌掺钇透明导电薄膜的制备及光电特性研究

采用射频磁控溅射法,室温下在玻璃衬底上制备出了具有良好附着性、低电阻率和高透过率的新型透明导电薄膜YZO(ZnO掺杂Y2O3简称YZO)。在薄膜厚度为600nm的情况下,研究了薄膜电学特性随溅射功率和溅射气压的变化情况。X射线衍射谱表明YZO薄膜是多晶膜,具有ZnO的六角纤锌矿结构,最佳取向为(002)方向。最佳溅射条件下制备的薄膜电阻率为8.71×10-4Ω.cm,在可见光范围内平均透过率达到92.3%,禁带宽度为3.57eV。     

射频功率对非晶硅薄膜光电性能的影响

采用等离子体辅助化学气相沉积(PECVD)技术,在Coming Eg 2000玻璃上制备非晶硅薄膜,研究了射频功率对薄膜光电性能的影响.结果表明:通过调节功率可获得具有高折射率,高吸收系数,低暗电导率的非晶硅薄膜.     

Preparation and photoelectric properties of Ti doped ZnO thin films annealed in vacuum

In the present paper, Ti doped ZnO films with higher conductive properties were grown on room temperature glass substrates by radio frequency magnetron sputtering and followed by annealing in vacuum. The microstructures and surface figures of the films were investigated by X-ray diffraction and scanning electronic microscopy, and its optical and electrical properties were measured using a four-point probe technique and 756-type spectrophotometer at room temperature. The results show that the preferred growth orientation of the films is (002) orientation, and after annealing in vacuum at 400 °C for 3 h, the average transmittance reduces from 90 to 80%, and resistivity reduces from 4.53 × 10^?2 to 8.78 × 10^?4 Ω cm.     

偏压对ITO薄膜生长模式和光电性能的影响

为明确溅射偏压对ITO薄膜性质的影响,用射频磁控溅射法于室温在玻璃衬底制备出ITO透明导电薄膜,研究了不同偏压下ITO薄膜的生长模式、光学和电学性能.结果表明:随着偏压的增加,薄膜沉积模式经历了沉积、沉积和扩散、表面脱附3种方式;AFM和SEM显示,偏压为100 V时,膜层表面光洁、均匀,粗糙度最小,均方根粗糙度为1.61 nm;XRD分析表明偏压会影响与薄膜的择优取向,偏压为100 V时,薄膜晶粒取向为(222)面;薄膜偏压为120 V时,薄膜的光电性能最佳,电阻率最低为2.59×10-4Ω.cm,可见光区的平均透过率在85%以上;偏压的大小使薄膜的吸收边发生了"蓝移"或"红移".     

a-Si:H薄膜的制备工艺对其光电特性的影响

采用MW-ECR CVD方法制备的a-SiH薄膜在模拟太阳光照射下进行光敏性(σp.σ d)和光致衰退测试.对比了有、无热丝辅助沉积的薄膜的光电特性,得出沉积温度是影响薄膜光敏性的主要因素,而适当温度的热丝辅助对于薄膜的光致衰退有一定延缓作用.     

Enhanced dielectric properties of modified Ta2O5 thin films

 Tantalum oxide (Ta₂O₅) is a promising high dielectric constant material for the DRAM applications because of its ease of integration compared to other complex oxide dielectrics. The dielectric constant and thermal stability characteristics of bulk Ta₂O₅ samples were reported to enhance significantly through small substitutions of Al₂O₃. However, this improvement in the dielectric constant of (1-x)Ta₂O₅-xAl₂O₃ is not clearly understood. The present research attempts to explain the higher dielectric constant of (1-x)Ta₂O₅-xAl₂O₃ by fabricating thin films with enhanced dielectric properties. A higher dielectric constant of 42.8 was obtained for 0.9Ta₂O₅–0.1Al₂O₃ thin films compared to that reported for pure Ta₂O₅ (25–30). This increase was shown to be closely related to a-axis orientation. Pure Ta₂O₅ thin films with similar a-axis orientation also exhibited a high dielectric constant of 51.7, thus confirming the orientation effect. The leakage current properties and the reliability characteristics were also found to be improved with Al₂O₃ addition. Received: 24 November 1998 / Reviewed and accepted: 7 December 1998     

Preparation and photoelectric properties of La-doped ZnO films

Among the various semiconducting metal oxide materials, ZnO films are highly attractive in the development of materials area. In order to improve the photoelectric properties of ZnO films, La-doped ZnO films were prepared by sol–gel method and the changes in conductive properties, light transmission and structure of the doped ZnO films were investigated. The research result shows that the La doping can improve the conductivity of the ZnO films, and when the La concentration increased, the resistivity first decreased and then increased, showing the “U” shaped variation. The resistivity of modified ZnO films drops to the lowest point of 1.84 Ω cm when the annealing temperature is 450 °C and La³⁺ concentration is 0.35 mol%. La doping can also improve the transmittance of ZnO films. The transmittance at the visible region of films is all over 82 %, and the highest value is up to 97 %. Annealing temperature also has an important impact on the electrical conductivity of the films: the resistivity declined further to 0.92 Ω cm as annealing temperature increased to 500 °C. But due to grain growth, it is not conducive to the improvement of light transmission properties.     

Effects of oxygen annealing on gas sensing properties of carbon nanotube thin films

Carbon nanotubes (CNTs) thin films deposited by plasma enhanced chemical vapor deposition have been investigated as resistive gas sensors towards NO₂ oxidizing gas. Effects of air oxidative treatment dramatically influence the nanotubes’ electrical resistance as determined by volt-amperometric measurements. In particular the electrical measurements show that electrical behavior of the CNT films can be converted from semiconducting to metallic through thermal treatments in oxygen. The electrical response was then measured exposing the films to sub-ppm NO₂ concentrations (100 ppb in air) at 165 °C. Upon exposure to NO₂, the electrical resistance of CNTs was found to decrease. The obtained results demonstrate that nanotubes could find use as a sensitive chemical gas sensor for (a) the fast response accompanied by a high sensitivity to sub-ppm NO₂ exposure, and (b) the precise recover of the base resistance value in absence of NO₂ at a fixed operating temperature, likewise indicating that intrinsic properties measured on as prepared nanotubes may be severely changed by extrinsic oxidative treatment effects.     

Anisotropy of the photoelectric properties of porous nanographite films

The influence of the orientation of platelike grains in nanographite (NG) films on the efficiency of photoelectric conversion of pulsed laser radiation has been studied. The initial orientation of NG grains perpendicular to the substrate surface was determined by a plasmachemical process used for the film deposition. A change in the orientation of grains in the film as a result of mechanical smoothing action leads to the appearance of anisotropy in the photoelectric properties of samples.     

In_2O_3：W薄膜的制备及光电性能研究

采用直流磁控溅射法制备了掺钨氧化铟（In2O3：W,IWO）薄膜,研究了制备工艺对薄膜表面形貌和光电性能的影响。结果表明薄膜的表面形貌与其光电性能有着紧密联系。氧分压显著影响薄膜的表面形貌进而对薄膜的光电性能产生影响,同时溅射时间的变化也显著影响薄膜的光电性能：随着氧分压以及溅射时间的升高,薄膜的电阻率均呈现先减小后增大的变化规律,在氧分压为2.4×10-1Pa条件下,制备样品的表面晶粒排布最细密,其电阻率达到6.3×10-4Ω.cm,载流子浓度为2.9×1020cm-3,载流子迁移率为34cm2/（V.s）,可见光平均透射率约为85%,近红外光平均透射率〉80%。     

氧分量对柔性衬底上WOx薄膜性能的影响

通过射频磁控溅射方法,在柔性PET衬底上低温沉积电致变色WOx薄膜.利用X射线衍射(XRD)、紫外-可见光分光光度计、X射线光电子能谱(XPS)分析所制备薄膜的微观结构、透光率、O元素的结合状态.结果表明,各氧分量下制备的WOx薄膜均为非晶态;氧分量0时制备的薄膜着、退色态透光率变化范围达到25%左右,具有较好的电致变色性能;XPS分析表明氧分量8%时氧空位含量最低,随着氧分量的继续增大,氧空位含量也增大.     

Dependence of ferromagnetic properties on growth oxygen partial pressure in boron-doped ZnO thin films

Boron-doped ZnO films were prepared by pulsed laser deposition technique. Magnetic, electrical, and optical properties of Zn_1?x B _x O films have been studied. It is found that the magnetic properties of the Zn_1?x B _x O films are sensitive to growth oxygen partial pressure. The films deposited under a high oxygen partial pressure of about 10?Pa appear to be ferromagnetic insulators at room temperature (RT). However, when the oxygen partial pressure decreases to 1.2?Pa, the films are non-ferromagnetic conductors at RT. Zn vacancies, which can be controlled by the oxygen partial pressure, are shown to be essential for realizing ferromagnetism (FM); on the other hand, the n-type nature of ZnO has no contribution to the FM observed in the B-doped ZnO films.     

Enhanced birefringence in vacuum evaporated silicon thin films

We report an experimental study of enhanced optical birefringence in silicon thin films on glass substrates. Form anisotropy is introduced as an atomic-scale morphological structure through dynamic control of growth geometry. The resulting birefringence is large compared with naturally anisotropic crystals and is comparable to two-dimensional photonic crystals. The films are fabricated with serial bideposition onto a substrate held at a fixed tilt angle relative to the impinging vapor. Films were analyzed by spectroscopic ellipsometry and scanning electron microscopy, the latter clearly revealing form anisotropy in a morphology of bunched columns perpendicular to the deposition plane with dimensions of hundreds of nanometers and smaller. The observed linear birefringence varies with wavelength and tilt angle, with a maximum of 0.4 at a 630-nm wavelength and 0.25 at 1500 nm.     

Permeation of oxygen through thin films of tetracene

A novel method of measuring the permeation of oxygen through thin films based on the oxidation of aluminium is described and results obtained for polycrystalline thin films of tetracene are reported. Thus for a tetracene film 375 nm thick the permeation was determined to be 0.39 × 10¹⁴ molecules sec^-1 cm^-2, a rate sufficiently large to cause the formation of additional interfaces in multilayer devices incorporating reactive materials, thereby inducing a drift in device characteristics. The results suggest that permeation is associated with the high density of grain boundaries.