0.7Pb(Mg_(1/3)Nb_(2/3))O_3-0.3PbTiO_3薄膜中自极化效应诱导的稳定热释电系数

采用sol-gel方法在Pt/Ti/SiO_2/Si衬底上制备了0.7Pb(Mg_(1/3)Nb_(2/3))O_3-0.3PbTiO_3,并研究了其铁电和热释电性质.X射线衍射结果表明薄膜具有高度的(111)择优取向.结果显示,在没有任何极化处理情况下,薄膜具有稳定的热释电系数,达到1.58×10~(-8) Ccm~(-2)K~(-1).当极化电场高于3倍薄膜的矫顽电场时,薄膜的热释电系数几乎保持不变.撤掉极化电场后,薄膜的热释电系数在10天后仅仅衰减4%左右,远比PZT薄膜稳定.研究发现不同方向极化处理,薄膜的热释电电流具有非对称性,即正向极化时热释电电流随电场增加而增大,负方向极化处理时,热释电电流随电场增加而减小.这些结果显示0.7Pb(Mg_(1/3)Nb_(2/3))O_3-0.3PbTiO_3表现出的优异热释电特性起源于薄膜中的自极化效应.     

沿[001]c极化0.70Pb(Mg_(1/3)Nb_(2/3))O_3-0.30PbTiO_3单晶的声表面波传播特性研究

以室温下弛豫铁电单晶0.70Pb(Mg_(1/3)Nb_(2/3))O_3-0.30PbTiO_3(PMN-30%PT)的材料参数为基础,研究了该晶体沿[001]c极化情况下,不同切型的声表面波传播特性.研究发现,X-切型的PMN-30%PT单晶是一种具有低相速度和高机电耦合系数的材料,同时存在许多能流角为零的传播方向,综合来看,X-切型的127°左右方向是声表面波的最佳传播方向.     

InP单晶的磁光和热电效应

对同一原生非掺杂InP单晶进行了一系列物理测试分析,研究了材料的光电导率与温度的依从关系,在295~318 K内,温度系数为-3×10-4eV/K,测得的室温禁带宽度为1.339 2 eV。禁带宽度Eg的磁性系数为8.6×10-4eV/T,材料的磁光特性测量结果为1.8 T。由此数据可得,约化电子有效质量mr*为0.067m0。由热电功率测量结果可得室温塞贝克系数为565μV/K。由此值以及霍尔测量值,可计算出状态密度有效质量md*为0.075 7m0。由该值和上面提到的约化电子有效质量可得到InP样品的价带电子有效质量mv*为0.591m0。     

Pb(Mg_(1/3)Nb_(2/3))O_3:PbTiO_3:Ba(Zn_(1/3)Nb_(2/3))O_3系弛豫铁电体的介电和电致伸缩性能

我们已经在Pb(Mg_(1/3)Nb_(2/3))O_3:PbTiO_3:Ba(Zn_(1/3)Nb_(2/3))O_3系中研制出一种具有2个不同的介电最大值的陶瓷介电体。两者都显示了扩散相变的铁电体的损耗特性。单个介电最大值的大小,可通过原材料中的Zn:Mg比来控制。适当选择组分就有可能在较大范围内获得几乎与温度无关的高介电率。这些介电体在强电场下有很大的电致伸缩形变,并且电致伸缩形变的温度变化率比其它弛豫铁电体小得多。     

钛铌镁酸铅[Pb(Mg1/3Nb2/3)O3-xPbTiO3]弛豫铁电体的研究进展

弛豫铁电体钛铌镁酸铅Pb(Mg_(1／3)Nb_2／3)O_3-xPbTiO_3(PMNT),简称PMWT,不仅具有良好的介电性能和电机械性能,还具有良好的电致伸缩和压电性能,是制备高K电容器、传感器和激发元等的良好材料。其在微电子领域的应用前景非常广阔,本文就Pb(Mg_(1／3)Nb_(2／3))O_3-xPbTiO_3,简称(PMNT)弛豫铁电体的最新研究进展进行综述性的报道。     

截止波长12μm的InAs0.04Sb0.96/GaAs的熔体外延生长及特性研究

用熔体外延(ME)法在半绝缘(100)GaAs衬底上成功生长出了截止波长为12 μm的InAs0.04Sb0.96外延层.傅立叶变换红外(FTIR)透射光谱揭示,InAsSb合金的禁带宽度被强烈变窄.通过分析InAs0.04Sb0.96外延层载流子浓度的温度依存性表明,其室温禁带宽度为0.105 5 eV,与透射光谱测得的数值很好地一致.通过测量12～300 K的吸收光谱,研究了InAs0.04Sb0.96/GaAs的禁带宽度的温度依存性.霍尔测量得出300 K下样品的电子迁移率为4.47×104 cm2/Vs,载流子浓度为8.77×1015 cm-3;77 K下电子迁移率为2.15×104 cm2/Vs,载流子浓度为1.57×1015 cm-3;245 K下的峰值迁移率为4.80×104 cm2/Vs.     

晶体与微声材料

9912747一种铌镁酸铅-钛酸铅晶体的铁电相变研究[刊]/张磊//压电与声光.—1999,21(2).—136～139(L)研究了 Pb(Mg_1/3Nb_2/3)O_3-PbTiO_3晶体的介电、热电和压电性质,温度测量范围为70K～600K。发现它不仅在474K 附近有一铁电-顺电相变,而且在180K附近还存在一个铁电-铁电相变。在相变温度区域里,     

化学溶液法制备的Ba0.9Sr0.1TiO3薄膜的结构及光学特性研究

采用高度稀释的前驱体溶液在LaNiO3(LNO)薄膜上沉积了Ba0.9Sr0.1TiO3(BST)薄膜。X-射线衍射分析表明BST薄膜呈高度的（100）择优取向。原子力显微镜测量发现制备的BST薄膜具有大的晶粒尺寸80-200nm。用椭偏光谱仪测量了光子能量为0.7-3.4eV范围内BST薄膜的椭偏光谱，用Cauchy模型描述BST薄膜的光学性质，获得了BST薄膜的光学常数谱和禁带宽度Eg=3.36eV。     

InAs/GaSb Ⅱ型超晶格的拉曼和光致发光光谱

采用分子束外延(MBE)技术,在GaSb(100)衬底上外延生长晶体结构完整和表面平整的Ⅱ型超晶格InAs(1.2 am)/GaSb(2.4 am).拉曼光谱表明:随着温度从70 K升高至室温,由于热膨胀作用和光声子散射过程中的衰减,超晶格纵光学声子拉曼频移向低波数方向移动5 cm-4,频移温度系数约为0.023 cm-1/K.光致发光(PL)峰在2.4～2.8 μm,由带间辐射复合和束缚激子复合构成,2.55 μm PL峰随温度变化(15～150 K)发生微小红移,超晶格中InAs电子带与GaSb空穴带带间距随温度变化比体材料的禁带宽度小.PL发光强度在15～50 K随温度升高而升高,在60～150 K则相反,并在不同温度段表现出不同的温度依赖关系.     

一种用(Pb_(1/2)Ni_(1/2))MnO_3改性的PbTiO_3压电陶瓷

1.引言 由于PbTiO_3压电陶瓷较难合成,因而使它的推广应用比PZT陶瓷晚。但是由于它的介电常数ε小(200左右),居里温度高(490℃),故在高频器件、红外器件等方面有应用前途。目前应用较广的(Ba,Pb)TiO_3-PTC陶瓷的转变温度就是利用PbTiO_3的高温特性来提高的。 本文介绍的是利用PbTiO_3的介电常数小、Kt大和频率稳定度高的特点,把它用作滤     

DC drift activation energy of LiNbO/sub 3/ optical modulators based on thousands of hours of active accelerated aging tests

Activation energy Ea in the drift of a separate dc bias port of x-cut LiNbO/sub 3/ (LN) optical modulators has been estimated based on thousands of hours of accelerated aging test data. The obtained drift curves show peaking and suggest an absence of catastrophically increasing bias voltages in these x-cut LN modulators. The Ea values calculated from the first positive drift slope, the time to peak and the succeeding negative drift slope were 1.39, 1.25, and 1.47 eV, respectively, suggesting Ea /spl sim/ 1.4 eV.     

XPS Investigation on Surface and Interface Electronic States of Alq3／ITO

The surface and interface electronic states of tris-(8-hydroxyquinoline)aluminum(Alq3)/indium-tin oxid(ITO)were measured and analyzed by X-ray photoelectron spectroscopy(XPS).The results indicated that, in Alq3 molecule,the binding energy(Eb)of Al atoms is 70.7eV and 75.1eV,corresponding to Al(O)and Al(Ⅲ）,respectively;The binding energy of C is 285.8eV,286.3eV,and 286.8eV,corresponding to C of C-C group,C-O,and C-N bond,respectively,N is the main peak locating at 401.0eV, corresponding to Natom of C-N=C.Oatoms mainly bond o H atom,with the binding energy of 533.2 eV.As the sputtering time of Ar^ ion bearn increases,Al2p,C1s,N1s,O1s,Ind3d5/2 and Sn3d5/2 peaks slightly shift towards lower binding energy,and Al2p,C1s and N1s peaks get weaker,which contributed to diffusing the oxygen,indium and tin in ITO into Alq3 layr.     

硅材料基本物理参数的高温模型与计算

介绍了硅材料本征载流子浓度ｎｉ、禁带宽度Ｅｇ、电子和空穴有效质量和及载流子迁移率μ的高温模型和计算结果。其中ｎｉ、Ｅｇ和、模型分别适用于３００～１２００Ｋ和３００～７００Ｋ，μ的模型在２５０～５００Ｋ定温区及１０１３～１０２０ｃｍ－３杂质浓度范围内，最大误差小于１３％。     

衬底温度对氧化钛薄膜的光学常数影响

采用沈阳CK-3高真空磁控溅射薄膜沉积设备在K9玻璃衬底上分别制备了衬底温度为150℃、200℃和250℃的氧化钛薄膜。XRD分析显示这三种温度制备的薄膜由于制备温度不高均没有明显衍射峰,为非晶薄膜。薄膜的光学常数由德国SENTECH SE 850型光谱型椭偏仪对薄膜测试得到,测试波长为300 nm～800 nm,采用Cauchy模型对测试结果进行拟合。结果发现随着制备衬底温度的增大,薄膜的折射率n和消光系数k都随着增大。在衬底温度从150℃增大到250℃时,薄膜的光学带隙从3.46 eV减小到3.02 eV。     

Charge transport mechanism of Al/Bi2Te3/Al thin film devices

Results of dielectric and conduction properties of vacuum evaporated Bi₂Te₃ thin film capacitors (Al/Bi₂Te₃/Al) have been reported in the frequency range 12 Hz to 100 kHz at various temperatures (303–423 K). The variation of capacitance and dielectric constant was found to be temperature and frequency dependent. The capacitance of the film decrease with increasing temperature which may be due to the expansion of the lattice and also due to the excitation of charge carriers at the sites of imperfection. The dielectric constant decreases with frequency at all temperature. This can be attributed to an interfacial polarization caused by space charge. The prevailing ac conduction mechanism in these films is hopping type. The activation energies were evaluated for various thicknesses and it is found to be 0.016 and 0.014 eV for the frequencies 200 Hz and 1 kHz, respectively.     

掺Te-GaAsP中深能级缺陷和大晶格弛豫(英文)

Deep-level transient spectroscopy and photocapacitance techniques (steady -state spectroscopy, transient spectroscopy, optical isothermal transient spectroscopy and initial slope technique) have been used to study the deep-level defects in Te-doped GaAs0.8P0.4. Two electron defects(A and B center) with thermal activation energies of 0.20 and 0.40eV and photoioni-zaton threshold energies of 0.60 and 1.31eV (T = 300K) have been detected. The B center has nonexponential transient capacitance and larger difference between thermal activation energy and photoionization threshold energy. It is suggested that B center belongs to the DX center type. The relation of photoionization section spectrosopy of the B center to the temperature has been studied. It has been found that the photoionization section spectroscopy has an obvious multi-phonon-widen effect. These results support the large -lattice-relaxation model of B center. From the photoionization section spectra at eight different temperatures (104-300K), we have obtained the photoionization threshold energies (1.41-1.31eV) and the lattice relaxation energies(1.25-1.15eV) of B center, which decrease with the increasing temperature in near linear rule. A configuration coordinate diagram has been drawn to describe the large-lattice-relaxation of B center.     

Study of electrical and optical properties of CNx thin films deposited by reactive magnetron sputtering

The study concerns the CN_x thin films deposited by Low Pressure Hot Target Reactive Magnetron Sputtering (LP-HTRMS). The thin film resistance changes with relative humidity (RH) and optical properties have been studied in the range of 300-653 K. The temperature coefficients of resistivity changes were −2.5%/K at 300 K and −0.5%/K at 500 K. The activation energy of conductivity E_ρ was found to be 0.21 eV in the case of unannealed sample and 0.44 eV when the sample was annealed at 653 K. The CN_x thin films fastness to light was tested in the range of 200-2500 nm by measuring their transmittance. The calculations of absorption carrying out with Tauc formula proved the dominance of indirect optical transitions with Eg energy of 1.04 eV and direct transitions of Eg 2.05 eV. The UV radiation was fully absorbed and light transmission was ca. 90% in the range from visible radiation to far infrared of 1000-2500 nm. The CN_x thin films showed the high resistance sensitivity to RH changes. At T = 300 K resistance changed from 882 M Ω for 36% RH to 386 k Ω for 85% RH. The CN_x thin films susceptibility to humidity was observed in case of both DC and AC current (100 Hz to 10 kHz) measurements. The Si₃N₄ or SiC buffer adhesive layer was incorporated between CN_x film and substrate and its influence on CN_x electrical properties was observed.     

Photoelectric properties of Zn3P2

Contacts on p-type Zn₃P₂ samples were made by vacuum evaporation of Au and In. The photo-voltage spectral response of Zn₃P₂ was measured on these contacts within the 0.5–1.4 μm range at temperatures 80 and 300 K. The effect of the lighting configuration on spectral plots is discussed and the origin of two peaks in the photoresponse is ascribed to both indirect and direct transitions in the energy band-structure of Zn₃P₂ with energies of about 1.34 and 1.63 eV at 80 K and 1.32 and 1.49 eV at 300 K, respectively. The effect of surface recombination on the photovoltage plots is also discussed.     

Activation energy of DC-drift of x-cut LiNbO3 opticalintensity modulators

The DC-bias-induced drift phenomenon in LiNbO₃ optical intensity modulators is a main cause of device wearout failure. In order to estimate the device lifetime, an activation energy value Ea of the drift is needed, and Ea=1.0 eV is already known for z-cut LiNbO₃ modulators. However, Ea of x-cut LiNbO₃ modulators is not known even though there is a possibility that the Ea depends on the crystal orientation. Here, Ea=1.4 eV is obtained experimentally for the x-cut LiNbO₃ modulator with a SiO₂ buffer layer from their drift measurements between 50°C-140°C     

ZnO纳米棒/薄膜结构的电沉积制备及性能

以阳离子表面活性剂——十六烷三甲基氯化铵(CTAC)作为添加剂,采用电沉积法在氧化铟锡玻璃基板上制备了ZnO薄膜。并研究了CTAC含量对阴极电流密度、结构、表面形貌、化学态和光学性能的影响。实验发现阴极电流密度和(002)择优取向随CTAC含量的增加而增加。电沉积氧化锌薄膜的表面形貌随CTAC含量的增加由小晶粒变为纳米棒,这表明CTAC在控制表面形貌方面有很重要的作用。X-射线光电子能谱表明Zn2p3/2,Zn2p1/2,O1s的峰位分别为1020.78eV、1046.88eV和530.8eV。CTAC对电沉积的影响可能是由于CTAC的吸附作用改变了不同晶面的表面能和生长动力学。此外,研究了ZnO薄膜的光学性能,结果表明当CTAC含量为3.0mmol/L时,薄膜具有较好的透光性和紫外发射性能。添加不同含量CTAC的ZnO薄膜禁带宽度介于3.27～3.52eV。