VO2薄膜对TEACO2激光响应特性的实验研究

报道了ＶＯ２薄膜在ＴＥＡＣＯ２激光照射下的相变特性的实验研究，结果表明：对于本文镀制的ＶＯ２薄膜，在偏置温度为５２℃条件下，ＴＥＡＣＯ２激光入射能量密度为１５０ｍＪ／ｃｍ＾２时，可使ＶＯ２薄膜发生相变，响应时间，５０ｎｓ，恢复时间≈２００μｓ。     

磁控溅射制备Ta2O5／TiO2薄膜及其光学与电学性能的研究

用直流平面磁控溅射沉积薄膜的方法在Ｓｉ和玻璃基片上制备了Ｔａ２Ｏ５／ＴｉＯ２混合薄膜,薄膜的透射光谱研究结果表明,在ＴｉＯ２掺入浓度为０到１７％,薄膜的折射率从２．０８到２．２３。薄膜折射率与掺入ＴｉＯ２的浓度呈近线性关系。薄膜的ＭＯＳ电容器的Ｉ－Ｖ和Ｃ－Ｖ测量表明,经过退火处理能够提高Ｔａ２Ｏ５／ＴｉＯ２混合薄膜的介电常数。     

锂离子注入对V2O5薄膜光吸收的影响

采用真空蒸发经热处理制备了Ｖ２Ｏ５薄膜,使用二电极恒流法从１Ｍ／ＬＬｉＣｌＯ４的ＰＣ电解质溶液向Ｖ２Ｏ５薄膜注入锂离子,形成ＬｉｘＶ２Ｏ５（０≤ｘ≤０．５４）,测量了Ｖ２Ｏ５薄膜近垂直反射和透射光谱,计算了光吸收系数。Ｘ射线衍射分析表明薄膜为微晶结构。吸收系数与光子能量关系曲线中存在两个不同的变化区域,光子能量较高部分,（αｈν）１２与ｈν有线性关系;较低部分,吸收光谱存在一个尾巴。这两个区域的分界能量取决于电子和锂离子的注入量。研究结果表明Ｖ２Ｏ５薄膜阳极电致变色起源于吸收边缘的移动,而阴极电致变色则来源于小极化子的吸收     

低压驱动薄膜电致发光特性及其机理的研究

采用低电阻率为Ｔａ２Ｏ５／ＳｉＯ２，Ｔａ２Ｏ５／Ａｌ２Ｏ３复合层制备了出低压驱动Ｚｎｓ：Ｍｎ薄膜电致发光器件，它的阈值电压在４０Ｖ以下，当驱动电压为６０Ｖ，频率为５０Ｈｚ，发光亮度在２００ｃｄ／ｍ＾２以上，这种器件具有其独特的亮度－电压特性和电荷存储量－电压特性，利用空间电荷限制电流模型分析了发光层中空间电荷，电场强度在这种低压驱动电致发光器件发光层中的分布特性，并对低压驱动薄膜电致发光机理，亮度     

沉积在α－Al＿2O＿3分形基底上Ag薄膜的特性

报道了采用磁控溅射法在α－Ａｌ＿２Ｏ＿３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Ａｌ＿２Ｏ＿３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．     

KH_2PO_4和（CH_3NHCH_2COOH）_3CaCl_2在高压下的状

在活塞圆筒式Ｐ～Ｖ关系测量装置上，研究了ＫＨ＿２ＰＯ＿４（ＫＤＰ）和（ＣＨ＿３ＮＨＣＨ＿２ＣＯ－ＯＨ）＿３ＣａＣＩ＿２［Ｔｒｉｓ－ｓａｒｃｏｓｉｎｅｃａｌｃｉｕｍｃｈｌｏｒｉｄｅ（ＴＳＣＣ）］在室温下、４．５ＧＰａ内的ｐ～Ｖ关系。实验结果表明：ＫＤＰ在２．１ＧＰａ左右有一个相变；ＴＳＣＣ在０．８ＧＰａ和３．２ＧＰａ左右各有一个相变。本工作还给出了它们在相变前后的状态方程，以及它们的格临爱森参数γＯ、体积模量Ｂ＿ｏ和Ｂ＿ｏ的压力导数Ｂ＿ｏ。     

SnO2超微粒薄膜的界面电子转移研究

用ＰＥＣＶＤ方法制备了ＳｎＯ２超微粒薄膜,此薄膜表面吸附很多氧,而且人对醇敏感,测量不同醇（甲醇、乙醇、正丙醇、乙二醇）的敏感性质和对薄膜者红外光谱测量,发现薄膜表面化学吸附Ｏ２＾２－、Ｏ２＾－、Ｏ＾－成为敏感活性中心是电子转移的桥梁。建立了电子转移的模型：表面Ｏ２＾－主要夺取醇中的质子,Ｏ＾－主要与醇中β－Ｃ上的Ｈ（与α－ＣＯＨ反式共平面）作用。醇的最终产物是醛类。解释了ＳｎＯ２超微粒薄膜作为传     

沉积在α-Al２Ｏ3分形基底上Ag薄膜的特性

报道了采用磁控溅射法在α－Ａｌ_２Ｏ₃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Ａｌ_２Ｏ₃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：     

偶氮基染料掺杂薄膜的双光子图象存储

研究了偶氮基染料掺杂薄膜ＭＯ－ＰＶＡ和ＥＯ－ＰＶＡ的双光子存储特性。在对薄膜用Ａｒ＾＋激光作预激发下实现了Ｈｅ－Ｎｅ激光的红光存储。获得了实时和短时存储照片。光电记录存储曲线，分析了双光四能级系统的存储机制。实现确定了最佳预激发功率约为０．２８Ｗ／ｃｍ＾２，最小Ｈｅ－Ｎｅ光可存储功率密度低于０．２Ｗ／ｃｍ＾２。     

纳米（Li2AO4）1—x—（ZrO2）x固体电解质陶瓷

用溶液凝胶共混法制备了纳米级的Ｌｉ２ＳＯ４－ＺｒＯ２复合固体电解质陶瓷。在复合陶瓷中，Ｌｉ２ＳＯ４、ＺｒＯ２的晶粒平均尺寸分别为４５、２７ｎｍ。晶粒尺寸的纳米化在材料中引入了大量的界面结构和表面结构。研究了掺不同量的纳米ＺｒＯ２第二相对Ｌｉ２ＳＯ４相变温度、相变行为及体系电导的影响，在纳米ＺｒＯ２作用下，Ｌｉ２ＳＯ４的相变温度可以降低１４０℃。在适当配比时，在５４０℃其离子电导可达到０．２Ｓ／ｃｍ     

Phase transitions in uniaxial ferromagnetic film covered by superconducting layers

The phase diagram and the single-domain uniform state for a uniaxial ferromagnetic film with the superconducting layers covering one or both sides of a ferromagnet are investigated. The superconductor is supposed to be a second-order one and the interaction between the magnetic sub-system and with the conductivity electrons in a superconductor is purely electromagnetic and the vortices in a superconductor are pinned. The critical thickness of the magnetic film for which the uniform state becomes absolutely stable is calculated when the external magnetic field is supposed to be in-plane of the film. It is shown that the critical thickness of the film from the magnetic material with the quality factor Q>1 monotonically decreases as the magnetic field increases in the range from zero value to the value of the transition field where the collinear phase transforms into the angular (canted) phase. Further the critical thickness increases with the increase of the field. The quasi-single-domain magnetic film states were considered when the film thickness was close to the critical one. It is shown that for a thin isolated magnetic film the domain period exponentially increases with the decrease of the film thickness. Such dependence, however for the film with double-side superconducting cover and close to the transition into the single domain state becomes logarithmic and for the film covered by superconductor only on the one side varies as the power series. The single-domain state existence and the asymptotic behaviour of the domain structure is explained by the features of the asymptotic behaviour of the domain walls within the system. As for isolated magnetic film and for a film with the superconductor cover layers the transition from the collinear phase to the inhomogeneous state is the second-order phase transition and the transition from the uniform angular phase to the inhomogeneous phase is the first-order transition.     

相变区硅薄膜拉曼和红外光谱分析

采用等离子体增强化学气相沉积(PECVD)技术制备了一系列不同氢稀释率下的硅薄膜,采用拉曼散射光谱和傅里叶红外光谱技术研究了非晶/微晶相变区硅薄膜的微观结构变化,将次晶结构(paracrystalline structure)引入到非晶/微晶相变区硅薄膜结构中,提出了次晶粒体积分数(f_p),用来表征硅薄膜中程有序程度。结果表明,氢稀释率的提高导致硅薄膜经历了从非晶硅到微晶硅的相变过程,在相变区靠近非晶相的一侧,硅薄膜表现出氢含量高、结构致密和中程有序度高等特性,氢在薄膜的生长中主要起到表面钝化作用。在相变区靠近微晶相的一侧,硅薄膜具有氢含量低、晶化率高和界面体积分数小等特性,揭示了氢的刻蚀作用主控了薄膜生长过程。采用扫描电子显微镜对样品薄膜的表面形貌进行分析,验证了拉曼散射光谱和傅里叶红外光谱的分析结果。非晶/微晶相变区尤其是相变区边缘硅薄膜结构特性优良,在太阳能电池应用中适合用作硅基薄膜电池本征层。     

嵌埋Ni颗粒的BaTiO_3/SrTiO_3薄膜的相变特性

采用高温X射线原位衍射和变温介电谱对SrTiO3基底上外延生长的BaTiO3(嵌埋Ni颗粒)薄膜进行了相变特性分析。从X射线衍射和介电谱的分析结果得出,BaTiO3的相变温度点转变为弥散的温度区间。在这个弥散的相变温度区间内,由于基底和薄膜之间的失配,以及嵌埋Ni颗粒的应力作用,薄膜的介电响应弥散剧烈,并偏离德拜弛豫。分析Cole-Cole图获知,BaTiO3薄膜在四方相转变为立方相的相变过程中同时存在几种极化机制,在高温状态下介电损耗随温度增大而增大。降温过程中,薄膜没有立即恢复四方相,可能是基底和Ni颗粒的共同作用影响了相变弛豫。     

掺钨VO_2薄膜的电致相变特性

采用直流磁控溅射与后退火工艺相结合的方法,在掺氟SnO_2(FTO)导电玻璃基底上制备了高质量的掺钨VO_2薄膜,对薄膜的结构、表面形貌和光电特性进行测试,分析了钨掺杂对其相变性能的影响.结果表明,室温下掺钨VO_2薄膜的阈值电压为4.2 V,观察到阈值电压下约有两个数量级的电流突变.随着温度升高,相变的阈值电压降低,且电流突变幅度减小.当施加8 V电压时,分别在不同温度下测试了掺钨VO_2薄膜的透过率.温度为20和50℃时,掺钨VO_2薄膜相变前后的红外透过率差量分别为23%和27%.与未掺杂的VO_2薄膜相比,掺钨VO_2薄膜具有相变温度低、阈值电压低和电阻率小的特点,在高速光电器件中有广阔的应用前景.     

Single-particle plasmon resonance spectroscopy of phase transition in vanadium dioxide

We demonstrate thermally controlled plasmon resonance modulation of single gold nanoparticles on vanadium dioxide thin films by performing dark-field spectroscopy measurements at different temperatures. The plasmon resonance of the nanoparticles exhibits a significant blueshift in the visible range when the vanadium dioxide film undergoes its insulator-to-metal phase transition around 67 °C. More importantly, the resonance shift shows a clear hysteresis, mirroring the behavior of the vanadium dioxide film. At a fixed wavelength, the scattering intensity of Au particles also shows a hysteretic behavior decorated with an overshoot before (after) the insulator-metal (metal-insulator) phase transition of the vanadium dioxide film, suggesting that the nanoparticle is probing local variations in the phase transition.     

Study of Phase Transition Properties in Epitaxial Ferroelectric Film

Based on the transverse Ising model and using decoupling approximation to the Fermi-type Green's function, we study the phase transition properties of the epitaxial ferroelectric film with one substrate. A general recursive equation of the ferroelectric thin film with two n-layer materials is obtained, which enables us to study the phase transition properties for any number layers forepitaxial ferroelectric thin film. With the help of this equation, we analyze the effect of the exchange interaction and the transverse field in the phase diagram, the influence to the polarizations and Curie temperature numerically. The results show that epitaxial ferroelectric film are able to induce a strong increase or decrease of Curie temperature to different exchange interactions and transverse fields within the epitaxial film layers. The theoreticalresults are in reasonable accordance with experimental data of different ferroelectric thin film.     

快速热处理制备相变氧化钒薄膜及其特性研究

采用直流对靶磁控溅射在Si<100>基底上沉积金属V薄膜, 然后分别在纯氧气环境和纯氮气环境下进行快速热处理制备具有 金属-半导体相变特性的氧化钒(VO_X)薄膜, 热处理条件分别为纯氧气环境下430℃/40 s, 450℃/40 s, 470℃/40 s, 450℃/30 s, 450℃/50 s, 纯氮气环境下500℃/15 s. 用X射线衍射仪、X射线光电子能谱、原子力显微镜 和扫描电子显微镜对薄膜的结晶结构、钒的价态和组分以及微观形貌进行分析. 利用四探针薄膜电阻测量方法和THz时域频谱技术分析薄膜的电学特性和光学特性. 结果表明: 金属V薄膜经过纯氧气环境450℃/40 s快速热处理 后形成了具有低相变特性的VO_X薄膜, 升温前后薄膜方块电阻变化幅度达到两个数量级, THz透射强度变化幅度较小. 为了提高薄膜的相变特性, 对制备的VO_X薄膜采用纯氮气环境500℃/15 s快速热处理, 薄膜的相变特性有了明显提升, 相变前后方块电阻变化达到3个数量级, THz透射强度变化达到56.33%.     

Phase transitions in barium–strontium titanate films on MgO substrates with various orientations

A comparative study of the lattice dynamic upon phase transitions in a polycrystalline Ba_0.8Sr_0.2TiO₃ (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.     

Terahertz spectroscopy studies on epitaxial vanadium dioxide thin films across the metal-insulator transition

We present results on terahertz (THz) spectroscopy on epitaxial vanadium dioxide (VO(2)) films grown on sapphire across the metal-insulator transition. X-ray diffraction indicates the VO(2) film is highly oriented with the crystallographic relationship: (002)(film)//(0006)(sub) and [010](film)//[2 ?1 ?10](sub). THz studies measuring the change in transmission as a function of temperature demonstrate an 85% reduction in transmission as the thin film completes its phase transition to the conducting phase, which is much greater than the previous observation on polycrystalline films. This indicates the crucial role of microstructure and phase homogeneity in influencing THz properties.     

Surface ferroelectric phase transition in multilayer polymer Langmuir films

The ferroelectric phase transition on the free surface of a polymer ferroelectric Langmuir-Blodgett film was studied by the optical second harmonic generation (SHG) technique. A hysteresis in the temperature dependence of the SHG intensity observed for a multilayer film of a poly(vinylidene fluoride)-trifluoroethylene copolymer in the vicinity of T≈15°C is a manifestation of the first-order ferroelectric phase transition in the topmost surface monolayer of the film.