不同衬底温度下生长的Bi1.5Zn1.0Nb1.5O7.0薄膜的XPS研究

采用固相反应法合成具有焦绿石立方结构的Bi1.5Zn1.0Nb1.5 O7(BZN)陶瓷靶材,采用脉冲激光沉积法在Pt/TiO2/SiO2/Si(100)基片制备立方BZN薄膜,衬底温度在500～ 700℃范围内变化.X射线衍射测量结果表明:当在500℃沉积BZN薄膜时,薄膜呈现出无定形态结构.随着衬底温度增加到550℃,薄膜开始晶化,并且显示出立方焦绿石结构.X射线光电子能谱也被用来研究BZN薄膜的结构状态和元素价态.测试得到的全谱表明:在BZN薄膜中,除了用于定标的C元素之外,只有Bi、Zn、Nb、O元素的特征峰,此外有Ti2p特征峰出现,可能来自底电极的TiO2缓冲层.各元素的窄谱扫描表明:Bi,Zn,Nb,O四种元素的化学价态分别是+3,+2,+5,-2.BZN薄膜在550℃结晶,随着衬底温度升高到600℃,金属阳离子的结合能的峰位向高能方向移动,然而O1s的特征峰位也向高能方向移动,这归因于薄膜中存在的氧空位.     

Sputtering pressure dependent composition and dielectric properties in Bi1.5MgNb1.5O7 thin films deposited at room temperature by RF magnetron sputtering

Bismuth magnesium niobate (Bi_1.5MgNb_1.5O₇, BMN) thin films with cubic pyrochlore phase and a highly [111] orientation were deposited by radio frequency magnetron sputtering at different pressures and crystallized at 700 °C in oxygen atmosphere. For low temperature deposition, the sputtering pressure has significant influence on the surface roughness and composition of the BMN thin film. The film deposited at 4.0 Pa has the closest stoichiometric composition and a lowest surface roughness, which exhibits large dielectric constant and low dielectric loss (158 and 0.0046 at 1 MHz, respectively). The dielectric tunability and the figure of merit (FOM) value are 16.4 % and 36 at a dc bias field of 0.8 MV/cm. The relative large dielectric constant, low dielectric loss, and high FOM value suggest that BMN thin films have potential application for tunable microwave device.     

Optimization of annealing temperature for YBa2Cu3O7 thin films post-annealed at a low oxygen partial pressure

Post-annealing of YBa₂Cu₃O₇ (YBCO) thin films is usually performed at 850–900°C in atmospheric-pressure oxygen. In this study, coevaporated YBCO films on LaAlO₃ were post-annealed in an oxygen partial pressure of 29 Pa at temperatures in the range 700–825°C. Zero resistance transition temperatures were 89–90 K. Both d.c. (room-temperature resistance and critical-current density) and a.c. parameters (extracted from eddy-current response measurements at 25 MHz) were monitored. The optimum temperature is close to 750°C, which is on the YBCO thermodynamic stability line at this low oxygen partial pressure.     

Bi4Ti3O12掺杂对(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7陶瓷结构与介电性能的影响

研究了Bi4Ti3O12掺杂对(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7(BZN)陶瓷烧结特性、相结构和介电性能的影响.采用传统的固相反应法制备样品,X射线衍射技术分析相结构,SEM观察表面形貌.结果表明,Bi4Ti3O12掺杂能有效地促进烧结,提高介电常数ε,降低介电损耗tgδ,优化介电频率温度系数αε.1000℃烧结8%(摩尔分数) Bi4Ti3O12掺杂的BZN陶瓷具有较好的介电性能ε=192,tgδ= 4.21×10-4,αε=-3.37×10-4/℃.     

Critical current density and microstructure of YBa2Cu3O7 thin films post-annealed at a low oxygen partial pressure

Post-annealing of thin films of YBa₂Cu₃O₇ (YBCO) has been performed at 29 Pa and 750°C. For films 0.6 μm thick, a critical current density >1 MA cm^?2 is obtained at 77 K, with a sharp eddy current response at 25 MHz. Microstructural investigation of these films by crosssectional and planar transmission electron microscopy reveals that the YBCO film has thec-axis normal to the plane of the substrate in a continuous sheet of varying thickness, frequently covering the entire thickness of the film. Mutually perpendicular rods with thec-axis in the plane of the LaAlO₃ substrate are also seen. The microstructure and critical current density of these films are compared with those of previously reported films post-annealed in atmosphericpressure oxygen.     

Characterization of Cd1−x Zn x Se thin films deposited at low temperature by chemical route

Optoelectronic technologically important pseudo-binary Cd_1−x Zn _x Se thin films with a variable composition (0 < x < 1) has been developed by chemical bath deposition method. The objective to study growth kinetics, physical, microscopic, compositional, optical, electrical and structural changes. Cd_1−x Zn _x Se have been deposited on non-conducting glass substrate in tartarate bath containing Cd⁺² and Zn⁺² ions with sodium selenosulphate with an aqueous alkaline medium at 278 K. The quality and the thickness of the films are depends upon deposition temperature, deposition time and pH, etc. X-ray diffraction (XRD), atomic absorption spectroscopy, optical absorption, scanning electron microscopy and thermoelectric technique characterized the films. The XRD study indicates the polycrystalline nature in single cubic phase over whole range of composition. Analysis of absorption spectra gave direct type band gap, the magnitude of which increases non-linearly as zinc content in the film is increased and dc electrical conductivity at room temperature was found to decreases from 10⁻⁷ to 10⁻⁸ (Ω cm)⁻¹. All the films show n-type conductivity. The promising features observed are the formation of continuous solid solutions in a single cubic phase.     

La掺杂对(Bi1.5Zn0.5)(Ti1.5Nb0.5)O7陶瓷组织和介电性能的影响

研究了La3+取代的(Bi1.5Zn0.5)(Ti1.5Nb0.5)O7基陶瓷(Bi1.5-xLaxZn0.5)(Ti1.5Nb0.5)O7(0.0≤x≤1 2,BLZNT)的结构与介电性能。采用传统的固相反应法制备了陶瓷样品,用XRD、SEM分析了样品的组织。在整个取代范围内,La3+取代的样品基本保持单一烧绿石相,稳定范围由容忍因子(RA/RB值)来确定;同时,随着La3+取代量的增加,晶胞常数先增后减。介电性能随结构变化而变化,其中介电性能为:ε=130～170,tanδ=～0.9×10-3(1MHz),并且掺杂La优化了BLZNT x样品高频端(>100kHz)的频谱特性。     

Lithium cobalt oxide thin films deposited at low temperature by ionized magnetron sputtering

Thin films of lithium cobalt oxides have been deposited by ionized magnetron sputter deposition with and without substrate heating. The technique uses a built-in radio frequency coil to generate an inductively coupled plasma (ICP) confined close to the substrate. The ICP plasma results in ion bombardment on the film surface, which serves as an extra energy input during film growth. Therefore, the film properties can be modified at a relatively lower temperature. The plasma irradiation induces variations of crystallography and morphology, as characterized by X-ray diffraction and scanning electron microscopy. The deposited films were tested as cathodes for lithium batteries, and the discharge curves were measured to compare the electrochemical properties of the deposited films. Applying suitable plasma irradiation, well crystallized LiCoO₂ phase was obtained at 350 °C (substrate temperature), which was much lower than the temperature (700 °C-750 °C) for conventional post anneal process. The LiCoO₂ films, fabricated under in-situ plasma irradiation and a relatively lower substrate temperature (350 °C), showed a discharge potential plateau at 4.3 V-3.8 V with a capacity of ∼ 110 mAh/g as discharged to 1.5 V.     

热丝CVD法低温制备的多晶硅薄膜质量对衬底依赖性的研究

以SiH4和H2作为反应气体,采用HWCVD的方法分别在石英玻璃、AZO、Si（100）和Si（111）衬底上制备了多晶硅薄膜。利用X射线衍射（XRD）,拉曼（Raman）光谱和傅里叶红外（FT-IR）吸收光谱研究了不同衬底对多晶硅薄膜的择优取向、晶化率和应力的影响,用SEM观察了多晶硅薄膜的表面形貌。研究发现在4种衬底上生长的多晶硅薄膜均为（111）择优取向。单晶硅片对多晶硅薄膜有很强的诱导作用,并且Si（111）的诱导作用优于Si（100）的诱导作用。AZO对多晶硅薄膜生长也有一定的诱导作用。通过计算薄膜晶态比,得到除以石英为衬底的样品外,其它3种样品的晶态比均在90%以上,尤其以单晶硅片为衬底的样品更高。石英玻璃、AZO和Si（100）上生长的多晶硅薄膜中均存在压应力。     

新型三明治结构铝诱导非晶硅薄膜低温晶化增强

本文对比探索了新型Al/α -Si/Al三明治结构与传统的Al/α -Si双层结构对铝诱导非晶硅薄膜低温晶化结果的影响,结果表明在相同的制备及退火条件下,前者更利于形成高度晶化的多晶硅薄 .膜.本研究工作利用拉曼光谱、掠入射X射线衍射、光学显微镜、方块电阻等表征方法探讨了薄膜厚度比和退火温度对金属诱导非晶硅薄膜晶化的程度、晶体结构以及电学性能的影响,最终制备出了电阻率仅为2.5 Ω·cm的多晶硅薄膜.     

Structural and electrical properties of room temperature pulsed laser deposited and post-annealed thin SrRuO3 films

Good quality strontium ruthenate (SrRuO₃) thin continuous films (15 to 125 nm thick) have been synthesized on silicon (100) substrates by room temperature pulsed laser deposition under vacuum followed by a post-deposition annealing, a route unexplored and yet not reported for SrRuO₃ film growth. The presence of an interfacial Sr₂SiO₄ layer has been identified for films annealed at high temperature, and the properties of this interface layer as well as the properties of the SrRuO₃ film have been analyzed and characterized as a function of the annealing temperature. The room temperature resistivity of the SrRuO₃ films deposited by laser ablation at room temperature and post-annealed is 2000 μΩ·cm. A critical thickness of 120 nm has been determined above which the influence of the interface layer on the resistivity becomes negligible.     

Optimization of annealing temperature for YBa2Cu3O7 thin films post-annealed at a low oxygen partial pressure

Post-annealing of YBa₂Cu₃O₇ (YBCO) thin films is usually performed at 850–900°C in atmospheric-pressure oxygen. In this study, coevaporated YBCO films on LaAlO₃ were post-annealed in an oxygen partial pressure of 29 Pa at temperatures in the range 700–825°C. Zero resistance transition temperatures were 89–90 K. Both d.c. (room-temperature resistance and critical-current density) and a.c. parameters (extracted from eddy-current response measurements at 25 MHz) were monitored. The optimum temperature is close to 750°C, which is on the YBCO thermodynamic stability line at this low oxygen partial pressure.     

铝诱导非晶硅薄膜低温晶化及结构研究

介绍了一种非晶硅薄膜低温晶化的新工艺－金属诱导非晶硅薄膜低温晶化。在非晶硅膜上蒸镀金属铝薄膜,而后于氮气保护中退火,实现了非晶硅薄膜的低温（＜600℃）晶化。利用X射线衍射、光学显微镜及透射电等测试方法,研究了不同退火工艺对非晶硅薄膜低温晶化的影响,确定了所制备的是多晶硅薄膜。     

射频磁控溅射法制备Bi2O3薄膜的电致变色性能研究

采用射频磁控溅射技术在ITO导电玻璃上沉积了Bi_2O_3薄膜,利用X射线衍射仪、原子力显微镜、X射线光电子谱对薄膜的微结构、表面形貌、成分和价态进行了表征。分析表明在空气气氛中350℃热处理的Bi_2O_3薄膜具有四方结构,属β-Bi_2O_3,该薄膜在-1.8-+3V的直流电压驱动下具有在透明和暗棕色之间转换的电致变色性能,着色和漂白过程中均没有其他价态(+3价以外)的Bi生成。研究发现Bi_2O_3薄膜在400-800nm的可见光波段平均透射率调制幅度可达44%,550nm处着色系数为9.6cm~2/C,该材料具有优良的电致变色性能。     

Film thickness dependence of critical current density for YBa2Cu3O7 films post-annealed at a low oxygen partial pressure

The variation of critical current density at 77 K as a function of film thickness was studied for YBa₂Cu₃O₇ films on (100) LaAlO₃ substrates. Film thicknesses were in the range 0.2–1.6μm. The films were deposited by co-evaporation and post-annealed under conditions which have previously resulted in high-quality films (750°C and an oxygen partial pressure of 29 Pa). The critical current density at 77 K exceeds 1 MA cm^?2 for the thinner films, and decreases with increasing film thickness in excess of about 0.4μm. The decrease is in rough agreement with a switch fromc-axis toa-axis growth at about this critical thickness. A good anticorrelation was found between room temperature resistivity and critical current density at 77 K. The results are compared to those obtained before by post-annealing at 850°C in 1 atm of oxygen.     

Structure and tribological properties of Ag films deposited at low temperature

The effects of substrate temperature on the structure and tribological properties of Ag films deposited at low temperatures (LT, 130-217 K) by arc ion plating (AIP) have been studied. The structure and morphology of the Ag films were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM). The results showed that there exist (1 1 1) and (2 0 0) preferred orientation transitions for decreasing temperature at different bias voltages. The tribological properties were evaluated by a ball-on-disk tribometer and wear tracks were analyzed by means of scanning electron microscopy (SEM). The results show that substrate deposition temperature significantly affected the wear of LT Ag films. For each bias voltage studied, the film showing the highest wear rate was deposited at the lowest temperature and the film with the lowest wear rate, (significantly lower than room temperature (RT) deposited Ag films), was deposited at a temperature between the highest and the lowest temperatures examined. The wear mechanism was discussed in terms of lubrication effect of film material transferred to the counterpart and its dependence on the microstructure of the original deposited film.     

Growth of Bi1.5MgNb1.5O7 thin films on Pt/Ti/SiO2/Si substrates by RF magnetron sputtering

In this letter, bismuth magnesium niobate (Bi_1.5MgNb_1.5O₇, BMN) thin films were deposited on Pt/Ti/SiO₂/Si substrates by using radio-frequency magnetron sputtering at various substrate temperatures. Based on the phase compositions and microstructures of these samples, we discussed the nucleation and growth of the BMN thin films and how the substrate temperature influenced these processes. The thin film begins to crystallize at 450 °C, and the annealed films were all composed of the cubic pyrochlore phase with a strong (222)-preferred orientation. The film deposited at 450 °C exhibited a large dielectric constant of 173, and a tunability of 26.6 % was obtained at a max dc bias field of 0.8 MV/cm.     

Bi2MoO6 dielectric thin films fabricated by thermal oxidation of Bi/Mo thin films at ultra-low temperature

Bi/Mo multilayer thin films are deposited on Si/SiO₂/Pt substrates by direct current magnetron sputtering. The effect of annealing temperature on the microstructure, dielectric and electrical properties of the as-sputtered films is characterized systematically. X-ray diffraction data indicate that the films annealed at 450–600 °C are a mixture of diphase with the main phase Bi₂MoO₆ and secondary phase Bi₂Mo₂O₉. Results of scanning electron microscope observation show that the films annealed at 500–550 °C are dense and uniform, in particular the films annealed at 500 °C exhibit optimal dielectric and electrical properties with dielectric constant as high as 37.5, dielectric loss 1.06 %, temperature coefficient of dielectric constant ?10.86 ppm °C^?1 at 1 kHz, and leakage current density of 1.46 × 10^?7 A mm^?2 at an electric field of 18.2 kV mm^?1. With the advantages of ultralow densification temperature (500 °C) and very high sputtering deposition rate (76 nm min^?1), it is anticipated that thermal oxidation method of the sputtered Bi/Mo thin films could be a promising technique for fabrication of Bi₂MoO₆ ceramic thin film embedded-capacitors.     

Internal stress and optical properties of Nb2O5 thin films deposited by ion-beam sputtering

The influence on the internal stress and optical properties of Nb2O5 thin films with ion-beam energy was investigated. Nb2O5 thin films were deposited on unheated glass substrates by means of ion-beam sputtering with different ion-beam voltage, Vb. The refractive index, extinction coefficient, and surface roughness were found to depend on the ion-beam energy. The stresses in thin films were measured by the phase-shifting interferometry technique. The film stress was also found to be related to Vb, and a high compressive stress of -0.467 GPa was measured at Vb = 850 V. The Nb2O5-SiO2 multilayer coatings had smaller average compressive stress as compared with single-layer Nb2O5 film.     

衬底温度对低温制备纳米晶硅薄膜的影响

采用传统的射频等离子体增强化学气相沉积技术,在较高的工作气压130Pa和较高的射频功率70W下,在＞100℃的低温下,以0.14nm/s速率制备出优质的纳米晶硅薄膜.研究结果表明,薄膜晶化率和沉积速率与衬底温度有密切关系.当衬底温度＞100℃,薄膜由非晶相向晶相转化,随着衬底温度的进一步升高,薄膜晶化率增大,当温度为300℃时,薄膜的晶化率达82%,暗电导率为10-4·cm-1数量级,激活能为0.31eV.当薄膜晶化后,沉积速率随衬底温度升高而略有增加.