Influence of target-substrate distance and composition on the preferential orientation of yttria-stabilized zirconia thin films

The use of yttria-stabilized zirconia (YSZ) thin films calls for a controlled deposition with full understanding on the influence of deposition parameters on the crystallographic properties of YSZ. YSZ thin films were deposited using magnetron sputtering from two sources, enabling to modify the sample composition in a flexible way. The influence of target-substrate (T-S) distance and the Y content on the crystallographic orientation were studied under different chamber pressures. Correlations were found under both conditions. This way, a two-dimensional map was obtained by showing the change in preferential orientation as a function of sample composition. This map shows the existence of two different trends depending on the pressure. At low pressure, the addition of Y and the decrease in T-S distance, change the orientation from [200] to a complete [111] out-of-plane orientation resulting in a competition between the fastest growth direction and the lowest surface energy. However, a different trend was observed at high pressure, where T-S distance and composition do not influence the preferential orientation of the film.     

ZnO缓冲层上低温生长Al掺杂的ZnO薄膜

采用射频磁控溅射法在ZnO缓冲层上制备了不同Al掺杂量的ZnO（AZO）薄膜。利用X射线衍射（XRD）、扫描电子显微镜（SEM）和光致发光（PL）等表征技术,研究了AZO薄膜的微观结构、表面形貌和发光特性。结果表明,随着Al掺杂量的增加,ZnO薄膜的择优取向性发生了改变,且当Al的掺杂量为0.81%（原子分数）时,（002）衍射峰与其它衍射峰强度的比值达到最大,表明适合的Al掺杂使ZnO薄膜的择优取向性得到了改善。在可见光范围内薄膜的平均透过率超过70%。通过对样品光致发光（PL）谱的研究,发现所有样品出现了3个发光峰,分别对应于以444nm（2.80eV）、483nm（2.57eV）为中心的蓝光发光峰和以521nm（2.38eV）为中心较弱的绿光峰。并对样品的发光机理进行了详细的探讨。     

Preparation and properties of YBa2Cu3O7 thin films on sapphire with Yttria-stabilized zirconia buffer layer

YBa₂Cu₃O₇ superconducting thin films were deposited onR-plane sapphire substrates with Yttria-stabilized zirconia buffer layer by laser ablation. The structure of the films was characterized by X-ray diffraction. Superconducting transitional temperatures as high as 90 K and critical current densities up to 2.2×10⁶ A/cm² (77 K) were achieved. The results of Auger depth profile showed that no obvious diffusion occurred between the substrate and the YBa₂Cu₃O₇ thin film.     

Morphology and growth of e-beam deposited YSZ thin films

Yttria-stabilized zirconium (YSZ) thin films were grown from the tetragonal phase of ZrO₂ stabilized by 8 wt% of Y₂O₃ (8% of YSZ) ceramic powders using e-beam deposition technique (EB-PVD). The influence of the type of substrate on the microstructure of deposited YSZ thin films was analysed. YSZ thin films (2-3 μm of thickness) were deposited on three different types of substrates: optical quartz (SiO₂), porous Ni-YSZ substrates and Alloy 600 (Fe-Ni-Cr). The dependence of the substrate temperature (from 20 to 600 °C) on the thin film structure and the surface morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that (i) the substrate temperature has an influence on the crystallite size, which varied between 12 and 50 nm, (ii) the substrate type has an influence on the growth mechanism of YSZ thin films, and (iii) a bias voltage applied to the substrate during the deposition of thin films has an influence on the densification of YSZ layers.     

The effect of deposition parameters on the properties of yttria-stabilized zirconia thin films

Yttria-stabilized zirconia (YSZ) films were deposited by RF magnetron sputtering in order to examine the effects of sputtering conditions on the properties of the resulting thin-films. X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS) and scanning electron microscopy (SEM) were used to characterize the films. Additionally, films were deposited on alumina bars to examine the effect of the coatings on the strength of a brittle substrate. RBS analysis indicated that the ratio of oxygen to zirconium in the films varied from 1.84 to 2.10. XRD showed that there was a wide variation in the amount of monoclinic and tetragonal phases that appeared to be related to the O:Zr ratio. Despite these variations, there was no significant difference found in flexural strength found among the groups of alumina bars that were coated with YSZ. The likely cause is the columnar grain morphology of the deposited thin-films, which does not allow strengthening mechanisms to become operative.     

半导体Si(111)上电沉积NiFe缓冲层薄膜

采用电化学沉积法,在半导体硅片上制备了具有纳米晶粒尺寸的NiFe缓冲层薄膜,并确定了获得Ni80Fe20合金的工艺条件.由SEM形貌观测分析,当薄膜名义厚度＞25 nm时,可形成连续性镀层.I-t暂态曲线及STM结果表明,NiFe薄膜在低过电位下以三维岛状模式生长,在高过电位下以二维层状模式生长,其RMS表面粗糙度最小值仅为0.5 nm.XRD结果表明,薄膜为面心立方Ni基固溶体结构,并具有明显的(111)晶面择优取向.当薄膜组成为Ni80Fe20时,各向异性磁电阻效应(AMR)最大,AMR值为1.8%.     

Heteroepitaxy of Ir films on silicon with a ceria/yttria stabilized zirconia buffer layer

Heteroepitaxial Ir films on Si(001) with a double ceria/yttria stabilized zirconia heteroepitaxial buffer layer were grown by magnetron sputtering. As-deposited CeO₂ films covered with {111} faceted pyramids resulted in iridium films with the [001] axis normal to the substrate plane. The buffered substrates annealed at 1115 °C have a smooth surface; Ir films on such substrates have the (111) orientation and consist of grains turned at 90° toward each other.     

Molecular layer deposition of ZrO2-based organic-inorganic nanohybrid thin films for organic thin film transistors

Molecular layer deposition (MLD) technique can be used for preparation of various organic-inorganic nanohybrid superlattices at a gas-phase. The MLD method is a self-controlled layer-by-layer growth process under vacuum conditions, and is perfectly compatible with the atomic layer deposition (ALD) method. In this paper, we fabricated a new type organic-inorganic nanohybrid thin film using MLD method combined with ALD. A self-assembled organic layer (SAOL) was formed at 170 °C using MLD with repeated sequential adsorptions of CC terminated alkylsilane and zirconium hydroxyl with ozone activation. A ZrO₂ inorganic nanolayer was deposited at the same temperature using ALD with alternating surface-saturating reactions of Zr(OC(CH₃)₃)₄ and H₂O. The prepared SAOL-ZrO₂ organic-inorganic nanohybrid films exhibited good mechanical stability, excellent insulating properties, and relatively high dielectric constant k (~ 16). They were then used as a 23 nm-thick dielectric for low voltage pentacene-based thin film transistors, which showed a maximum field effect mobility of 0.63 cm²/V s, operating at − 1 V with an on/off current ratio of ~ 10³.     

Structural and optical properties of high quality ZnO thin film on Si with SiC buffer layer

ZnO thin films are grown on Si substrates with SiC buffer layer using ion plasma high frequency magnetron sputtering. These substrates are fabricated using a technique of solid phase epitaxy. With this technique SiC layer of thickness 20-200 nm had been grown on Si substrates consisting pores of sizes 0.5-5 μm at SiC and Si interface. Due to mismatching in lattice constants as well as thermal expansion coefficients, elastic stresses have been developed in ZnO film. Pores at the interface of SiC and Si are acting as the elastic stress reliever of the ZnO films making them strain free epitaxial. ZnO film grown on this especially fabricated Si substrate with SiC buffer layer exhibits excellent crystalline quality as characterized using X-ray diffraction. Surface topography of the film has been characterized using Atomic Force Microscopy as well as Scanning Electron Microscopy. Chemical compositions of the films have been analyzed using Energy Dispersive X-ray Spectroscopy. Optical properties of the films are investigated using Photoluminescence Spectroscopy which also shows good optical quality.     

Buffer layers for high-Tc thin films on sapphire

Buffer layers of various oxides including CeO₂ and yttrium-stabilized zirconia (YSZ) have been deposited onR-plane sapphire. The orientation and crystallinity of the layers were optimized to promote epitaxial growth of YBa₂Cu₃O_7– (YBCO) thin films. An ion beam channeling minimum yield of 3% was obtained in the CeO₂ layer on sapphire, indicating excellent crystallinity of the buffer layer. Among the buffer materials used, CeO₂ was found to be the best one for YBCO thin films onR-plane sapphire. HighT _c andJ _c were obtained in YBCO thin films on sapphire with buffer layers. Surface resistances of the YBCO films were 4 m at 77 K and 25 GHz.     

Deposition of metal chalcogenide thin films by successive ionic layer adsorption and reaction (SILAR) method

During last three decades, successive ionic layer adsorption and reaction (SILAR) method, has emerged as one of the solution methods to deposit a variety of compound materials in thin film form. The SILAR method is inexpensive, simple and convenient for large area deposition. A variety of substrates such as insulators, semiconductors, metals and temperature sensitive substrates (like polyester) can be used since the deposition is carried out at or near to room temperature. As a low temperature process, it also avoids oxidation and corrosion of the substrate. The prime requisite for obtaining good quality thin film is the optimization of preparative provisos viz. concentration of the precursors, nature of complexing agent, pH of the precursor solutions and adsorption, reaction and rinsing time durations etc. In the present review article, we have described in detail, successive ionic layer adsorption and reaction (SILAR) method of metal chalcogenide thin films. An extensive survey of thin film materials prepared during past years is made to demonstrate the versatility of SILAR method. Their preparative parameters and structural, optical, electrical properties etc are described. Theoretical background necessary for the SILAR method is also discussed.     

BN薄膜的制备及BPXN1-X薄膜的紫外光敏特性

采用热丝和射频等离子体辅助化学气相沉积方法(HF-PECVD),以单晶硅为衬底在低温(< 500℃)条件下沉积氮化硼(BN)薄膜材料.通过傅立叶变换红外光谱(FTIR)、 X射线衍射(XRD)及扫描电镜(SEM)对薄膜样品的组成和结构进行了分析,探讨了温度和等离子体对沉积BN薄膜的影响.此外,用紫外-可见光分光光度计(UV)测试了石英衬底上生长磷掺杂氮化硼(BPXN1-X)薄膜样品的紫外吸收特征,分析了磷掺杂对 BN光学能隙的调节作用以及 BPXN1-X薄膜在紫外空间探测领域的应用前景.结果表明,以单晶硅和光学石英玻璃为衬底在低温条件下用 HF-PECVD方法可以沉积较高质量的 BN薄膜,BN的光学能隙宽度通过磷的掺杂可以得到连续调节,在紫外空间光探测领域具有很大的应用潜力.     

Deposition of CdS thin films onto Si(111) substrate by PLD with femtosecond pulse

The effect of laser fluence (laser incident energy in the range of 0.5-1.5 mJ/pulse with the same laser spot size of 0.5 mm × 0.7 mm) on the structural quality and optical properties synthesized by femtosecond pulsed-laser deposition has been studied. The structural quality and optical properties of the deposited CdS thin films were investigated by X-ray diffraction, atomic force microscopy and photoluminescence measurement. The studies revealed an improvement in the structural quality and optical properties of the CdS thin films with increasing the laser fluence in some range. However, too high laser fluence could lead to the structural quality and optical properties of the CdS thin films to degrade. We defined the optimum laser incident energy was around 1.2 mJ/pulse. And the kinetic energy of the plasma produced by femtosecond laser strongly affects the structure and properties of the deposited CdS thin films.     

Deposition of GaN films on (1 1 1) Si substrates by alternate supply of TMG and NH3

GaN films were grown on (1 1 1) Si substrates at 1000 °C by separate admittances of trimethylgallium (TMG) and ammonia (NH₃). To achieve high quality GaN films, the optimization in growth temperature and layer thickness of AlN buffer layer between GaN film and Si substrate is required. Cross-sectional transmission electron microscopic observations of the GaN/(1 1 1)Si samples show a nearly parallel orientation relationship between the (0 0 0 1) planes of GaN film and the (1 1 1) planes of Si substrate. Room temperature photoluminescence spectra of high quality GaN films show a strong near band edge emission and a weak yellow luminescence. The achievement of high quality GaN films on (1 1 1) Si substrates is believed to be attributed to enhancement in surface mobilities of the adsorbed surface species and adequate accommodation of lattice mismatch between high temperature AlN buffer layer and Si substrate.     

Stability of microcrystalline silicon solar cells with HWCVD buffer layer

Microcrystalline silicon solar cells deposited by VHF-PECVD with or without HWCVD grown p/i interface buffer layer were investigated. We studied long-term stability under storage in ambient atmosphere and performed light soaking experiments. Cells with i-layers covering a wide range of crystalline volume fractions were studied. All cells were stable or degraded slightly after storage for 2 years in air, regardless of crystalline volume fraction or presence of p/i buffer interface. Upon light soaking all cells show efficiency degradation to more or less extent depending on crystal volume fraction of the i-layer and the presence of the buffer layer: the solar cell with high crystal volume fraction are nearly stable, cells with high amorphous volume fraction degrade by up to 20%. The solar cell with HWCVD buffer layer shows better stability in the high efficiency range of relative efficiency degradation typically less than 10% after 1000 h AM 1.5 light soaking. The efficiency degradation is mainly caused by Voc and FF deterioration while Jsc is almost stable.     

磁控溅射法制备TiO2空穴缓冲层的有机发光器件

采用磁控溅射方法在ITO表面制备了不同厚度的TiO2超薄膜用做有机发光二极管（OLEDs）的空穴缓冲层,使OLEDs（ITO／TiO2／TPD／Alq3／Al）的发光性能得到很大改善。研究TiO2缓冲层厚度对器件性能影响的结果表明,当TiO2缓冲层厚度为1nm,电流密度为100mA／cm^2时,器件的发光效率为2cd／A,比未加缓冲层器件的发光效率增加了近一倍。这是由于加入适当厚度的TiO2缓冲层限制了空穴的注入并且提高了空穴与电子注入之间的平衡。     

Simulation studies on the effect of a buffer layer on the external parameters of hydrogenated amorphous silicon p-i-n solar cells

Device modeling of p-i-n junction amorphous silicon solar cells has been carried out using the amorphous semiconductor analysis (ASA) simulation programme. The aim of the study was to explain the role of a buffer layer in between the p-and i-layers of the p-i-n solar cell on the external parameters such as dark current density and open circuit voltage. Investigations based on the simulation of dark I–V characteristics revealed that as the buffer layer thickness increases the dark current for a given voltage decreases.     

Ba0.5Sr0.5 TiO3薄膜、Ba0.1Sr0.9 TiO3/YBa2 Cu3O7-δ异质薄膜的制备及介电性能研究

铁电钛酸锶钡(BSTO)薄膜具备十分优越的铁电/介电性能,在可调谐微波器件和动态随机存储器(DRAM)方面显示出十分诱人的应用前景.而YBa2Cu3O-δ(YBCO)高温超导薄膜作为其电极引入,明显降低了微波损耗,能够大大优化器件的性能.本文针对微波器件性能要求对比了各种常用基片的性能参数,描述了目前BSTO薄膜与BSTO/YBCO异质薄膜制备中存在的问题以及薄膜介电性能测试表征方法.利用脉冲激光沉积(PLD)技术成功制备出结构完整和质量较高的Ba0.5Sr0.5TiO3薄膜.同时,在1.2°斜切LaAlO3基片上研制有Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ异质双层膜,在1MHz频率、77K温度条件下,其介电常数为1200,介电损耗为0.0045,±30V直流偏压时可调性达到60%,在液氮温度下表现出良好的应用前景.     

Plasma oxidation of Al thin films on Si substrates

In this study, Al thin films deposited on silicon wafers by direct current magnetron sputtering were oxidized under radio frequency 13.56 MHz O₂ plasma at temperatures up to 550 °C. During oxidation, plasma powers as well as oxidation temperature and time were varied to investigate the oxidation behavior of the Al films. X-ray photoelectron spectroscopy and Auger electron spectroscopy results show that the apparent alumina could be observed after O₂ plasma treatment with powers above 200 W as well as at temperatures above 250 °C. However, no alumina increment could be discerned after individual either heat treatment at 550 °C or plasma treatment at room temperature. The thickness of alumina layers increased remarkably with plasma power and could reach about 60 nm when undergone 400 W O₂ plasma treatment at 550 °C for 2 h. Moreover, the thickness of alumina increased parabolically with time during plasma oxidation aided by thermal treatment. The deduced activation energy of such plasma oxidation was 19.1 ± 0.5 kJ/mol.     

Growth and characteristics of ZnO films on growth side of freestanding diamond substrate dependent on buffer layer thickness

We report the growth and properties of highly c-axis oriented ZnO films, by radio-frequency magnetron sputtering, on the growth side of freestanding chemical vapor deposited diamond film-substrate. Low-temperature ZnO buffer layer is required for the formation of continuous ZnO films. The morphology, structure, and optical properties of the ZnO films deposited are strongly dependent on the thickness of the buffer layer. The optimized thickness of ZnO buffer layer is about 10 nm to realize high-quality ZnO films having small compressive stress and high intensity ultraviolet emission. The ZnO/diamond (growth side) system is available for the applications in numerous fields, especially for high performance surface acoustic wave devices.