8.0nm反射式偏振膜的设计和制备

讨论了软X射线反射式偏振膜的设计原理和方法,利用设计软件模拟设计了8.0nm处的Mo/B4C偏振膜.对影响多层膜性能的参量进行了详细的误差分析.利用磁控溅射镀膜机进行了偏振膜的制备研究,X射线小角衍射测量了多层膜的周期厚度,测量数据的拟合结果与设计值吻合很好.

用不同的Mo靶溅射功率制备Mo／Si多层膜

用磁控溅射法制备了周期厚度和周期数均相同的Mo／Si多层膜，用原子力显微镜和小角X射线衍射分别研究了Mo靶溅射功率不相同时，Mo／Si多层膜表面形貌和晶相的变化。随后在国家同步辐射实验室测量了Mo／Si多层膜的软X射线反射率。研究发现，随着Mo靶溅射功率的增大，Mo／Si多层膜的表面粗糙度增加，Mo的特征X射线衍射峰也增强，Mo／Si多层膜的软X射线峰值反射率先增大后减小。

Mo／Si软X射线多层膜的界面粗糙度研究

用磁控溅射法分别制备了以Mo膜层和Si膜层为顶层的Mo／Si多层膜系列，利用小角X射线衍射确定了各多层膜的周期厚度。以不同周期数的Mo／Si多层膜的新鲜表面近似等同于同一多层膜的内界面，通过原子力显微镜研究了多层膜界面粗糙度随膜层数的变化规律。并在国家同步辐射实验室测量了各多层膜的软X射线反射率。研究表明：随着膜层数的增加，Mo膜层和Si膜层的界面粗糙度先减小后增加然后再减小，多层膜的峰值反射率先增加后减小。

基底温度对直流磁控溅射ITO透明导电薄膜性能的影响

用直流磁控溅射法制备透明导电锡掺杂氧化铟(ITO)薄膜,靶材为ITO陶瓷靶,组分为m(In2O3):m(SnO2)=9∶1。运用分光光度计、四探针测试仪研究了基底温度对薄膜透过率、电阻率的影响,并用X射线衍射(XRD)仪对薄膜进行结构分析。计算了晶面间距和晶粒尺寸,分析了薄膜的力学性质。实验结果表明,在实验设备条件下,直流磁控溅射ITO陶瓷靶制备ITO薄膜时,适当的基底温度(200℃)能在保证薄膜85%以上高可见光透过率下,获得最低的电阻率,即基底温度有个最佳值。薄膜的结晶度随着基底温度的提高而提高。

High refractive index TiO2 film deposited by electron beam evaporation

The well known 'crystal seed' theory is first applied in this work to prepare TiO2 film: a high refractive index rutile TiO2 film is grown by electron beam evaporation on the rutile seed formed by 1100 degrees C annealing. The average n is larger than 2.4, by far the highest in all the authors' TiO2 films. The films are characterised by optical properties, microstructure and surface morphologies. It is found that the refractive index shows positive relation with the crystal structure, grain size, and packing density and roughness of the film. The film has lower density of granularity and nodule defects on the surface than those of the film deposited by magnetron sputtering. The result shows attractive application in complex filter and laser coatings.

Interface as the origin of ferromagnetism in cobalt doped ZnO film grown on silicon substrate

We have investigated the magnetic properties of Co-doped zinc oxide (ZnO) film deposited on silicon substrate by magnetron sputtering. Co ions have a valence of 2+ and substitute for Zn sites in the lattice. By using a chemical etching method, an extrinsic ferromagnetism was demonstrated. The observed ferromagnetism is neither associated with magnetic precipitates nor with contamination, but originates from the silicon/silicon oxide interface. This interface ferromagnetism is characterized by being temperature independent and by having a parallel magnetic anisotropy. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2989128]

Enhancement of conductivity and transmittance of ZnO films by post hydrogen plasma treatment

We studied the effects of hydrogen plasma treatment on the electrical and optical properties of ZnO films deposited by radio frequency magnetron sputtering. It is found that the ZnO H film is highly transparent with the average transmittance of 92% in the visible range. Both carrier concentration and mobility are increased after hydrogen plasma treatment, correspondingly, the resistivity of the ZnO H films achieves the order of 10(-3) cm. We suggest that the incorporated hydrogen not only passivates most of the defects and/or acceptors present, but also introduces shallow donor states such as the V-O-H complex and the interstitial hydrogen H-i. Moreover, the annealing data indicate that H-i is unstable in ZnO, while the V-O-H complex remains stable on the whole at 400 degrees C, and the latter diffuses out when the annealing temperature increases to 500 degrees C. These results make ZnO H more attractive for future applications as transparent conducting electrodes.

Enhancement of field emission of the ZnO film by the reduced work function and the increased conductivity via hydrogen plasma treatment

The ZnO films deposited by magnetron sputtering were treated by H/O plasma. It is found that the field emission (FE) characteristics of the ZnO film are considerably improved after H-plasma treatment and slightly deteriorated after O-plasma treatment. The improvement of FE characteristics is attributed to the reduced work function and the increased conductivity of the ZnO H films. Conductive atomic force microscopy was employed to investigate the effect of the plasma treatment on the nanoscale conductivity of ZnO, these findings correlate well with the FE data and facilitate a clearer description of electron emission from the ZnO H films.

Effect of the oxygen concentration on the properties of Gd2O3 thin films

Gd2O3 thin films were deposited on Si (100) substrates at 650degreesC by a magnetron sputtering system under different Ar/O-2 ratios of 6:1, 4:1 and 2:1. The effect of the oxygen concentration on the properties of oxide thin films was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy and capacitance-voltage (C-V)measurement. X-ray diffraction shows that the structure of oxide films changed from the monoclinic Gd2O3 phase to cubic Gd2O3 phase when the oxygen concentration increased. According to C-V measurement, the dielectric constant value of the samples deposited at different Ar/O-2 ratios is about 12. (C) 2004 Elsevier B.V. All rights reserved.

Structural, magnetic properties and photoemission study of Ni-doped ZnO

Nickel-doped ZnO (Zn1-xNixO) have been produced using rf magnetron sputtering. X-ray diffraction measurements revealed that nickel atoms were successfully incorporated into ZnO host matrix without forming any detectable secondary phase. Ni 2p core-level photoemission spectroscopy confirmed this result and suggested Ni hits it chemical valence of 2 +. According to the . We studied the electronic magnetization measurements, no ferromagnetic but paramagnetic behavior was found for Zn0.86Ni0.14O. We studied the electronic structure of Zn0.86Ni0.14O by valence-band photoemission spectroscopy. The spectra demonstrate a structure at similar to 2 eV below the Fermi energy E-F, which is of Ni 3d origin. No emission was found at E-A, suggesting the insulating nature of the film. (c) 2005 Elsevier Ltd. All rights reserved.

Influence of nitridation time on the morphology of GaN nanorods synthesized by nitriding Ga2O3/ZnO films

Gallium nitride (GaN) nanorods were synthesized by nitriding Ga2O3/ZnO films which were deposited in turn on Si (111) substrates using radio frequency (RF) magnetron sputtering system. In the nitridation process, ZnO was reduced to Zn and Zn sublimated at 950 degrees C. Ga2O3 was reduced to Ga2O and Ga2O reacted with NH3 to synthesize GaN nanorods with the assistance of the sublimation of Zn. The morphology and structure of the nanorods were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED). The composition of GaN nanorods was studied by Fourier-transform infrared spectrophotometer (FTIR). The synthesized nanorods is hexagonal wurtzite structured. Nitridation time of the samples has an evident influence on the morphology of GaN nanorods synthesized by this method. (c) 2006 Elsevier B.V. All rights reserved.

Dependence of intrinsic defects in ZnO films on oxygen fraction studied by positron annihilation

Defects in ZnO films grown by radio-frequency reactive magnetron sputtering under variable ratios between oxygen and argon gas have been investigated by using the monoenergetic positron beam technique. The dominate intrinsic defects in these ZnO samples are O vacancies (V-O) and Zn interstitials (Zn-i) when the oxygen fraction in the O-2/Ar feed gas does not exceed 70% in the processing chamber. On the other hand, zinc vacancies are preponderant in the ZnO Elms fabricated in richer oxygen environment. The concentration of zinc vacancies increases with the increasing (2) fraction. For the oxygen fraction 85%, the number of zinc vacancies that could trap positrons will be smaller. It is speculated that some unknown defects could shield zinc vacancies. The concentration of zinc vacancies in the ZnO films varies with the oxygen fraction in the growth chamber, which is in agreement with the results of photoluminescence spectra.

Structural and photoluminescent properties of ternary Zn1-xCdxO crystal films grown on Si(111) substrates

The ternary Zn1-xCdxO (0less than or equal toxless than or equal to0.6) alloying films with highly c-axis orientation have been deposited on Si(111) substrates by direct current reactive magnetron sputtering method. X-ray diffraction measurement indicates that the wurtzite-type structure of ZnO can be stabilized up to nominal Cd content x similar to 0.6 without cubic CdO phase separation. The lattice parameter c of Zn1-xCdxO increases almost linearly from 5.229 Angstrom (x = 0) to 5.247 Angstrom (x = 0.6), indicating that Cd substitution takes place on the Zn lattice sites. The photoluminescence spectra of the Zn1-xCdxO thin films measured at 12 K display a substantial red shift (similar to0.3 eV) in the near-band-edges (NBEs) emission of ZnO: from 3.39 eV of ZnO to 3.00 eV of Zn0.4Cd0.6O. The direct modulation of band gap caused by Zn/Cd substitution is responsible for the red shift effect in NBE emission of ZnO. (C) 2003 Elsevier Science B.V. All rights reserved.

SiO2/Ta interface reaction in magnetic multilayers and its influence on Ta buffer layers

Ta is often used as a buffer layer in magnetic multilayers. In this study, Ta/Ni81Fe19/Ta multilayers were deposited by magnetron sputtering on sing-crystal Si with a 300-nm-thick SiO2 film. The composition and chemical states at the interface region of SiO2/Ta were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that there is an 'inter-mixing layer" at the SiO2/Ta interface due to a thermodynamically favorable reaction: 15 SiO2 + 37 Ta = 6 Ta2O5 + 5 Ta5Si3. Therefore, the Ta buffer layer thickness used to induce NiFe (111) texture increases.

Determination of oxidation states in magnetic multilayers

X-ray photoelectron spectroscopy has been used to characterize the oxidation states in Ta/NiOx/Ni-81/Fe-19/Ta magnetic multilayers prepared by rf reaction and dc magnetron sputtering. The exchange coupling field and the coercivity of NiOx/Ni81Fe19 are studied as a function of the ratio of Ar to O-2 during the deposition process. The chemical states of Ni atoms in the interface region of NiOx/NiFe have also been investigated by x-ray photoelectron spectroscopy and the peak decomposition technique. The results show that the ratio of Ar to O-2 has a great effect on the chemical states of nickel in NiOx films. Thus the exchange coupling field and the coercivity of Ta/NiOx/Ni81Fe19/Ta are seriously affected. Also, the experiment shows that x-ray photoelectron spectroscopy is a powerful tool in characterizing magnetic multilayers.