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1.
利用脉冲激光法研究了在(100)SrTiO3(STO)、(100)LaAlO3(LAO)和(100)Y-ZrO2(YSZ)衬底上外延生长LaCuO4(LCO),La1.85Sr0.15CuO4(LSCO),Nd1.85Ce0.15CuO4(NCCO)和Pr2CuO4(PCO)薄膜的工艺技术。利用X光衍射仪检测了不同条件下制备的薄膜样品结构和取向。X射线衍结果表明,在事适的制膜条件下可以在这三种衬底  相似文献   

2.
孟进芳  邹广田  崔启良  赵永年 《物理学报》1994,43(10):1739-1744
合成了LaxBi2-xTi411系列样品,并完成了它们的喇曼光谱和x射线衍射测量;结果表明,该体系在X=1.2经历了一次相变,且相变与最低频声子模随X的变化有关。La0.2Bi1.8·Ti411的相变温度为200℃。初步获得La2Ti411的结构为正交结构。 关键词:  相似文献   

3.
异质外延生长钙钛矿结构氧化物薄膜   总被引:1,自引:0,他引:1  
影响直接外延生长氧化物薄膜的因素有很多,最主要的是保证氧化物薄膜的正确成相和在单晶衬底上成核.直接外延生长时,衬底温度影响到薄膜的成相.衬底温度还影响薄膜的生长动力学,并因此影响薄膜的外延生长取向.由于薄膜是首先在衬底表面成核、成相并生长的,因此衬底材料晶格的影响是不容忽视的.衬底材料(或异质外延材料)与薄膜的相互作用是影响外延生长的最直接因素,而晶格常数失配会造成薄膜样品中存在应力并影响样品性质.利用脉冲激光淀积法,我们成功地外延生长了YBa2Cu3O7超导薄膜、Sr0.5Ba0.5TiO3铁电介电薄膜、La0.7Ca0.3MnO3铁磁巨磁电阻薄膜、La0.5Sr0.5CoO3导电薄膜等多种具有钙钛矿结构的氧化物功能薄膜.以这些钙钛矿结构氧化物薄膜的外延生长为例,本文讨论影响氧化物薄膜异质外延生长的因素  相似文献   

4.
对快速退火后用共蒸发B3方法实现重掺杂硼的硅分子束外延层的电学特性进行了研究.1100℃退火可以使得外延层中载流子浓度提高4倍,空穴的霍耳迁移率与相同浓度下硅体材料的水平相当;外延层与衬底之间载流子浓度转变陡峭,获得了晶体质量良好的外延层. 关键词:  相似文献   

5.
黄桐凯  中村哲朗 《物理学报》1994,43(11):1840-1846
测量了BaSn1-xSbx3-δ和Ba1-yLaySnO3-δ样品的低温电阻率和磁化率.实验结果表明,在较低温度区域,两类样品的导电机制均是传导电子的范围可变跳跃。而在较高温度区域,BaSn1-xSbx3-δ样品的电导主要是电子从定域态到扩展态的跃迁所贡献,Ba1-yLaySnO3-δ样品的电导则可能来源于电子的最近邻跳跃。 关键词:  相似文献   

6.
(Ba_(1-x)K_x)BiO_3电子结构与超导电性   总被引:1,自引:0,他引:1       下载免费PDF全文
沈耀文  张志鹏  陈龙海  黄美纯 《物理学报》1996,45(10):1737-1743
用第一原理的LDF-LMTO-ASA超元胞法,模拟由X射线吸收谱精细结构测定的BaBiO中,Bi有两种价态Bi3+和Bi5+及与之相应的两种不同键长的Bi—O八面体,以及K掺杂对晶体结构的影响.计算了Ba4Bi412,(BaK)Bi412,(BaK)Bi26,(BaK)Bi412,K2Bi26(简记为(404),(314),(112),(134),(022))五种“样本”的电子结构.结果表明,(404)和(314)分别为Eg=1.6eV及Eg=1.5eV的半导体,其它“样本”为金属.总能的分析表明(134)是不稳定的,故溶解极限为x=0.5.以“取样”方式按伯努利分布确定任意组分各“样本”的概率,进而计算了(Ba1-xx)BiO电子结构随组分的变化.最后用逾渗模型说明了超导转变温度Tc在x=0.25附近的突变 关键词:  相似文献   

7.
报道了采用磁控溅射法在α-Al3分形基底上沉积Ag薄膜表面的形貌、结晶状态以及其V-I特性.结果表明:分形的Al3基底导致Ag薄膜具有起伏不平的结构、较差的结晶状态并且存在大量的孔洞,它们同样受基底温度和薄膜厚度的影响.在一定的厚度范围内,Ag薄膜呈现反常的非线性I(V)特性,其行为也受薄膜厚度、基底温度和测试环境的强烈影响. 关键词:  相似文献   

8.
采用磁控溅射方法在(100)YSZ基底上沉积了YBa2Cu3O7/SrTiO3/YBa2Cu3O7异质外延三层膜,利用交流磁化率和四引线电阻测量的方法确定了三层膜的超导性能,利用X射线衍射和透射电子显微镜研究了三层膜的结构特征.研究结果表明,膜层的结晶质量较好,临界转变温度Tc在83.K和86.7K之间.YBCO膜层中的绝大多数甚至全部)晶粒为C取向,在有些膜中只存在少量的a或b取向的YBCO晶粒.三层膜中层界面比较清晰但不十分平整.在膜/基界面处有8-10nm厚的过渡层,它由多晶的BaZrO3组成.膜层和(10)YSZ基底之间具有如下的外延生长关系YSZ[001]//YBCO[110]//SrTjO3[110];YSZ(100)//YBCO(001)//SrTiO3(001).  相似文献   

9.
利用X射线衍射和扫描电子显微镜对不同衬底温度下电子束蒸发的CaS∶TbF3电致发光薄膜的结晶性和表面形貌进行了研究.通过对薄膜的透射率和漫反射率的测量研究了薄膜的致密性.X射线衍射表明衬底温度在220到580℃范围之间,电子束蒸发的CaS∶TbF3电致发光薄膜为多晶立方晶相.随着衬底温度的提高,CaS∶TbF3薄膜的表面形貌发生显著的变化,薄膜的致密性增加,从而增加了电致发光亮度.  相似文献   

10.
用深能级瞬态谱(DLTS)和恒温电容瞬态等技术研究了浅杂质注入LEC半绝缘GaAs的γ射线辐照缺陷。在Be-Si共注的LEC半绝缘GaAs中,γ射线辐照引入一电子陷阶E2,并且大大增强了原有的E01(0.298)和E02(0.341)等缺陷,同时明显地瓦解了原有的少子陷阱H03。在单纯注Si的LEC半绝缘GaAs中,γ射线辐阳引进了E'01(0.216),E'02(0.341),E'2,E'4和E'5(0.608)等缺陷。其中E01和E'01是新发现的和γ辐照有关的GaAs缺陷。和低阻衬底同质外延GaAs相比,Be-Si共注LEC半绝缘GaAs具有较低的γ射线辐照缺陷引入率,与此相反,单纯注Si的LEC半绝缘GaAs具有较高的γ射线辐照缺陷的引入率。 关键词:  相似文献   

11.
何萌  刘国珍  仇杰  邢杰  吕惠宾 《物理学报》2008,57(2):1236-1240
采用激光分子束外延技术,利用两步法,在Si单晶衬底上成功地外延生长出TiN薄膜材料.原子力显微镜分析结果显示, TiN薄膜材料表面光滑,在10 μm×10 μm范围内,均方根粗糙度为0842nm.霍耳效应测量结果显示,TiN薄膜在室温条件下的电阻率为36×10-5Ω·cm,迁移率达到5830 cm2/V·S,表明TiN薄膜材料是一种优良的电极材料.X射线θ—2θ扫描结果和很高的迁移率均表明,高质量的TiN薄膜材料被外延在Si衬底 关键词: 激光分子束外延 TiN单晶薄膜 外延生长  相似文献   

12.
《Current Applied Physics》2009,9(5):1009-1013
We present here a comparative study on structural and magnetic properties of bulk and thin films of Mg0.95Mn0.05Fe2O4 ferrite deposited on two different substrates using X-ray diffraction (XRD) and dc magnetization measurements. XRD pattern indicates that the bulk sample and their thin films exhibit a polycrystalline single phase cubic spinel structure. It is found that the film deposited on indium tin oxide coated glass (ITO) substrate has smaller grain size than the film deposited on platinum coated silicon (Pt–Si) substrate. Study of magnetization hysteresis loop measurements infer that the bulk sample of Mg0.95Mn0.05Fe2O4 and its thin film deposited on Pt–Si substrate shows a well-defined hysteresis loop at room temperature, which reflects its ferrimagnetic behavior. However, the film deposited on ITO does not show any hysteresis, which reflects its superparamagnetic behavior at room temperature.  相似文献   

13.
Epitaxial VO2 films were prepared on the TiO2 (001) substrates by the excimer-laser-assisted metal–organic deposition (ELAMOD). The quality of the epitaxial films obtained by irradiation with a KrF laser was found to be affected by the film structure obtained after preheating at 500 or 300°C. When the films containing crystal domains, which were obtained by preheating at 500°C, were irradiated with the laser at room temperature under a base pressure of 250 Pa, epitaxial and polycrystalline VO2 phases were simultaneously formed. In contrast, when the amorphous films containing organic components, which were obtained by preheating at 300°C, were irradiated with the laser at room temperature in air, a single phase of epitaxial VO2 was formed. By using thermal simulations, we determined that the formation of the epitaxial phase was affected both by the temperature distribution within the film during the laser irradiation and by the laser intensity at the interface between the substrate and the film. The latter factor is considered to play a role in the nucleation of crystallization, causing the epitaxial phase to form preferentially compared to the polycrystalline phase in the amorphous matrix of the films. These results indicate that the ELAMOD process is effective for the fabrication of epitaxial VO2 films at low temperature.  相似文献   

14.
A comparative study of the lattice dynamic upon phase transitions in a polycrystalline Ba0.8Sr0.2TiO3 (BST) film on a Pt substrate and in epitaxial BST films grown on various sections of an MgO substrate has been performed by Raman spectroscopy. It has been found that different sequences of phase transitions take place in these films. The BST/Pt films demonstrate the same sequence of phase transitions that is observed in the bulk ceramics. The hardening of a soft mode in BST/(001)MgO and BST/Pt films shows that the transition from the tetragonal ferroelectric phase to the paraelectric phase has features of the displacement-type phase transition and also the order–disorder phase transition. When approaching the ferroelectric transition temperature, the soft mode in the BST/(111)MgO film is softened, following the Cockran law, which indicates the displacement-type phase transition.  相似文献   

15.
We report the heteroepitaxial growth of SrTiO3 thin films on Si(001) by hybrid molecular beam epitaxy (hMBE). Here, elemental strontium and the metal‐organic precursor titanium tetraisopropoxide (TTIP) were co‐supplied in the absence of additional oxygen. The carbonization of pristine Si surfaces during native oxide removal was avoided by freshly evaporating Sr into the hMBE reactor prior to loading samples. Nucleation, growth and crystallization behavior as well a structural properties and film surfaces were characterized for a series of 46‐nm‐thick SrTiO3 films grown with varying Sr to TTIP fluxes to study the effect of non‐stoichiometric growth conditions on film lattice parameter and surface morphology. High quality SrTiO3 thin films with epitaxial relationship (001)SrTiO3 || (001)Si and [110]SrTiO3 || [100]Si were demonstrated with an amorphous layer of around 4 nm thickness formed at the SrTiO3/Si interface. The successful growth of high quality SrTiO3 thin films with atomically smooth surfaces using a thin film technique with scalable growth rates provides a promising route towards heterogeneous integration of functional oxides on Si. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)  相似文献   

16.
Epitaxial (Co,Fe) nitride films were prepared on TiN buffered Si(001) substrates by dual-target reactive co-sputtering method. With lower Co content, thin films mainly consist of (Co x Fe1?x )4N phase. With higher Co content, STEM EELS found no N signal in the thin film, and, combined with XRD results, shows that fcc Co is the main phase of the thin films instead of Co4N. The N2 atmosphere is helpful to induce the fcc Co phase formation during dual-target reactive co-sputtering deposition. For the films with less Co content, the RT magnetization measurements show similar magnetic properties as epitaxial Fe4N(001) films, while increasing the Co content, the resulting fcc Co thin films show biaxial anisotropy with the [110] in-plane easy axis.  相似文献   

17.
This paper reports the first results obtained on monobarium gallate thin films grown on silicon and platinum coated substrates by pulsed laser deposition. The influence of oxygen background pressure and substrate (or post-annealing) temperature on the film properties was studied. The films were characterized by XRD, RHEED, AFM, photoelectron and electrical impedance spectroscopy. The structure analysis showed that the films crystallized into a hexagonal phase, most probably into (metastable) α-BaGa2O4. Depending on deposition conditions, films with different (from nearly epitaxial to polycrystalline) textures were obtained.  相似文献   

18.
《Solid State Ionics》2006,177(26-32):2347-2351
Superlattice thin films of a perovskite-type oxide proton conductor SrZr0.95Y0.05O3/SrTiO3 were fabricated and their structural and electrical properties were investigated. X-ray and electron diffraction analysis reveals that the thin films were epitaxially grown on MgO (001) substrate. High-resolution transmission electron microscopy observation shows that the multilayered structure is uniform and that the interfaces between the different layers are of low roughness. Misfit dislocations are found at the interface, having Burgers vectors in direction a[100]. From the local elemental analysis, the interdiffusion of Zr and Ti between layers was not observed, while Mg impurities diffused from the substrate are observed. The in-plane electrical conductivity of the thin films was measured by impedance spectroscopy. The conductivity of the superlattices shows a higher value than a single SrZr0.95Y0.05O3 film. The activation energies of the epitaxial layers show relatively higher value than the corresponding single crystal.  相似文献   

19.
Epitaxial (001) aluminum nitride (AlN) thin films on (111) Si substrates are prepared using pulsed-laser deposition. The epitaxial structure of the as-prepared thin films is characterized by checking the X-ray-diffraction θ-2 θ scan and pole-figure, using scanning electron microscopy, infrared radiation (IR) spectroscopy and Raman spectroscopy. The surface acoustic-wave resonance at 345 MHz for a 1.5 μm thick AlN film on a (111) Si substrate is observed using an inter-digital electrode. Received: 18 September 2001 / Accepted: 29 January 2002 / Published online: 3 June 2002 RID="*" ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: liujm@nju.edu.cn  相似文献   

20.
Epitaxial Gd2O3 thin films were successfully grown on Si (001) substrates using a two-step approach by laser molecular-beam epitaxy. At the first step, a ~0.8 nm thin layer was deposited at the temperature of 200 °C as the buffer layer. Then the substrate temperature was increased to 650 °C and in situ annealing for 5 min, and a second Gd2O3 layer with a desired thickness was deposited. The whole growth process is monitored by in situ reflection high-energy electron diffraction (RHEED). In situ RHEED analysis of the growing film has revealed that the first Gd2O3 layer deposition and in situ annealing are the critical processes for the epitaxial growth of Gd2O3 film. The Gd2O3 film has a monoclinic phase characterized by X-ray diffraction. The high-resolution transmission electron microscopy image showed all the Gd2O3 layers have a little bending because of the stress. In addition, a 5–6 nm amorphous interfacial layer between the Gd2O3 film and Si substrate is due to the in situ high temperature annealing for a long time. The successful Gd2O3/Si epitaxial growth predicted a possibility to develop the new functional microelectronics devices.  相似文献   

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