The effects of thermal annealing in NH3 -ambient on the p-type ZnO films

Thermal annealing in NH₃-ambient was carried out to form p-type ZnO films. The properties were examined by X-ray diffraction (XRD), Hall-effect measurement, photoluminescence (PL), and secondary ion mass spectrometry (SIMS). Electron concentrations in ZnO films were in the range of 10¹⁵–10¹⁷/cm³ with thermal annealing in NH₃-ambient. The activation thermal annealing process was needed at 800 C under N₂-ambient to obtain p-type ZnO. The electrical properties of the p-type ZnO showed a hole concentration of 1.06×10¹⁶/cm³, a mobility of 15.8 cm²/V s, and a resistivity of 40.18 Ω cm. The N-doped ZnO films showed a strong photoluminescence peak at 3.306 eV at 13 K, which is closely related to neutral acceptor bound excitons of the p-type ZnO. The incorporation of nitrogen was confirmed in the SIMS spectra.     

Electric and magnetic behaviour in double doped La2/3＋4x/3Sr1/3-4x/3Mn1-xMgxO3

The double-doped La2/3＋4x/3Sr1/3-4x/3Mn1-xMgxO3 samples with fixed Mn^3＋/Mn^4＋ ratio equal to 2/1 are investigated by means of magnetism and transport measurements. Phase separation is observed at temperature higher than T^onset c for x = 0.10 and 0.15. For x = 0.10, rather strong phase separation induces drastic magnetic random potential and results in the localization of carriers. Thus, the varlable-range hopping process dominates. For other samples, there is no or only weak phase separation above T^onset c. Thus, thermal activation mechanism is responsible for the high temperature transport behaviour. For x = 0.20 and 0.25, unexpected AFM behaviour is observed at low temperature. All these results are well understood by considering the special role of the ＂double-doping＂.     

Synthesis and electroluminescence properties of fluorene containing arylamine oligomer

We synthesized a blue fluorescent fluorene containing arylamine oligomer, bis(9,9,9′,9′‐tetra‐n‐octyl‐2,2′‐difluorenyl‐7‐yl)phenylamine (DFPA), and investigated its electroluminescence (EL) properties. Organic EL devices with a structure of glass/indium‐tin oxide/acid‐doped poly(thiophene) derivative/DFPA/aluminum complex (BAlq)/cesium‐doped macrocyclic compound/Al were fabricated. The device exhibited blue emission, peaking at 432 nm, from the DFPA layer. The maximum luminance of 1800 cd/m² and an external quantum efficiency of 1.5% were observed. Copyright © 2004 John Wiley & Sons, Ltd.     

以蓝色发光材料DPVBi为基质的白色发光器件

白色有机发光器件是实现彩色平板显示的重要方案之一。利用蓝色发光材料DPVBi[4，4′—(2，2—苯乙烯基)—1，1′—联苯]掺杂红光染料DCJTB[4—氰甲烯基—2—叔丁基—6—(1，1，7，7—四甲基久洛尼定基—9—烯炔基—4H—吡喃)]作发光层制备了白色发光器件。研究了DPVBi掺杂不同浓度IDCJTB薄膜的光致发光性质，根据光致发光结果，制备了以DPVBi掺杂不同浓度DCJTB作发光层的电致发光器件，其结构为ITO／GuPc／NPB／DPVBi：DCJTB／Alq3／LiF／Al。当DCJTB质量分数为0．0008时，器件实现了白色发光(色度x=0．25，y=0．32)，电致发光和光致发光的掺杂比例基本相符，表明器件的白色发光主要是由基质DPVBi向掺杂剂DCJTB的能量传递产生的。研究还发现：白色器件随电压升高，光谱中蓝色成分相对于红色成分的比例略有增加，文章对此现象进行了分析。该白光器件在14V时达到最高亮度7822cd／cm^2，在20mA／cm^2电流密度下的亮度为-489cd／cm^2，最大流明效率为1．75lm／W。     

Dy掺杂对Sr2Bi4Ti5O18铁电陶瓷性能的影响

用传统固相烧结法制备了Sr₂Bi_4-xDy_xTi₅ O₁₈(SBDT-x, x=0—0.20)陶瓷样品. x射线衍射分析表明, 微量的Dy掺杂没有影 响Sr₂Bi₄Ti₅O₁₈(SBTi) 原有的层状钙钛 矿结构. 通过研究样品的介电特性, 发现Dy掺杂减小了材料的损耗因子, 降低了样品铁电- 顺电相转变的居里温度. 铁电性能测量结果表明, 随Dy含量的增加, SBDT-x系列样品的剩余 极化先增大, 后减小. 当Dy掺杂量为0.01时, 剩余极化达到最大值, 约为20.1 μC·cm^-2. 掺杂引起剩余极化的变化, 与材料中缺陷浓度、内应力以及晶格畸变程度等因 素有关, 是多种作用机理相互竞争的结果. (Bi₂O₂)²⁺ 层通常被看作是绝缘层和空间电荷库, 对材料的铁电性能起关键作用. 掺杂离子进入(Bi2O₂)²⁺层会导致铁电性能变差. 关键词： 2Bi₄Ti₅O₁₈陶瓷')" href="#">Sr₂Bi₄Ti₅O₁₈陶瓷 Dy掺 杂 铁电性能 居里温度     

多晶Sr2Fe1－xAlxMoO6的晶粒内低场磁电阻效应

用传统的固相反应法合成了Fe位掺杂Al的双钙钛矿型氧化物Sr2Fe1-xAlxMoO6 (x=00，005，010，015，03)多晶材料. x射线衍射和扫描电子显微分析显示，在Fe位掺杂Al既没有引入杂相，也没有明显改变Sr2FeMoO6多晶材料的晶粒尺寸和晶界状态. 非磁性Al离子的掺杂使晶粒内部磁有序区细化成更小的区域，同时使反铁磁区内的磁耦合作用变弱. 这一方面提高了亚铁磁区磁化方向的磁场灵敏度；另一方面也降低了反铁磁区对自旋相关电子的散射；两方面的共同作用使Sr2FeMoO6的低场磁电阻效应明显增强，但这种尺寸效应也使材料的磁电阻在高温下下降得更快. 关键词： 低场磁电阻 掺杂 自旋极化电子