Degradation of current–voltage and low frequency noise characteristics under negative bias illumination stress in InZnO thin film transistors

The instabilities of indium–zinc oxide thin film transistors under bias and/or illumination stress are studied in this paper. Firstly, illumination experiments are performed, which indicates the variations of current–voltage characteristics and electrical parameters(such as threshold voltage and sub-threshold swing) are dominated by the stress-induced ionized oxygen vacancies and acceptor-like states. The dependence of degradation on light wavelength is also investigated. More negative shift of threshold voltage and greater sub-threshold swing are observed with the decrease of light wavelength.Subsequently, a negative bias illumination stress experiment is carried out. The degradation of the device is aggravated due to the decrease of recombination effects between ionized oxygen vacancies and free carriers. Moreover, the contributions of ionized oxygen vacancies and acceptor-like states are separated by using the mid-gap method. In addition, ionized oxygen vacancies are partially recombined at room temperature and fully recombined at high temperature. Finally, low-frequency noise is measured before and after negative bias illumination stress. Experimental results show few variations of the oxide trapped charges are generated during stress, which is consistent with the proposed mechanism.     

RTP电光晶体的生长及其器件性能研究

磷酸氧钛铷(RbTiOPO₄,简称RTP)是综合性能优异的电光晶体,具有电光系数高、半波电压低、激光损伤阈值高、器件小巧、环境适应性强等优点,已成为新一代电光器件应用材料,非常适合用作电光开关、电光调制器等。激光系统的发展迫切需求更高功率、更高重复频率和更窄脉宽激光用高性能电光晶体,基于此,本文选用富Rb的高[Rb]/[P]摩尔比值生长体系,通过顶部籽晶熔盐法生长出高质量RTP晶体,测试了晶体或器件的光学均匀性、重复频率、插入损耗、消光比和抗激光损伤阈值,结果表明,该晶体的光学均匀性为7.3×10^-6 cm^-1,重复频率为501 kHz,插入损耗为0.49%,消光比为31.57 dB,激光损伤阈值为856 MW/cm²。     

2-(4-氯代苯甲酰基)苯甲酸配合物光致发光研究

以Eu3+,Tb3+为中心离子,2-(4-氯代苯甲酰基)苯甲酸(HCBBA)为第一配体,邻菲咯啉(Phen)、三苯基氧膦(TPPO)、二苯亚砜(DPSO)为第二配体,合成了多种铕铽的二元和三元配合物,并测试其荧光效能,以研究配体的加入对中心离子发光强度的影响。结果表明,合成的配合物均发出Eu(Ⅲ)和Tb(Ⅲ)的特征荧光,但相对强度明显不同。在铕与2-(4-氯代苯甲酰基)苯甲酸根(CBBA)形成的配合物体系中,Phen和DPSO显示了较强的敏化作用,且Phen敏化效果更强,而TPPO则对配合物荧光有猝灭作用。在Tb-CBBA体系中,DPSO表现出很强的敏化作用, Phen和TPPO却对配合物荧光起猝灭作用,且TPPO猝灭效果更强。经红外推测,羧酸根均以双齿桥式与Eu3+和Tb3+配位;在3 200～3 600 cm-1出现水的弱的羟基的伸缩振动吸收峰,表明配合物中含有结晶水。     

基于函数映射的快速傅里叶变换算法

给出了一种新的快速傅里叶变换算法.算法利用了傅里叶变换因子C_N^kn、S_N^kn的对称特性,将函数序列x(n)个数压缩至四分之一.对其压缩后的函数序列,按其相邻函数值之差映射为函数p(n),同时对傅里叶变换因子C_N^kn、S_N^kn按累进求和映射为A_N^kn、B_N^kn.不同于FFT算法要求N为2的整数次幂,该算法中N可为任何偶数.对诸如方波、三角波、锯齿波及可分解为阶梯波的光学图象、特别是二值光学图象,能极大地减少计算量,某些情形低于FFT算法的计算量.     

Eu2+掺杂KCaCl3晶体的生长及发光性能

通过坩埚下降法生长出不同物质的量分数Eu²⁺掺杂的KCa_1-xEu_xCl₃(x=0.005、0.01、0.02、0.03、0.05)单晶,并对晶体进行了X射线粉末衍射、热重、透过率、光致发光光谱、衰减时间、X射线激发发射光谱等测定。通过相图及结构分析,判断出该晶体为一致熔融化合物,并得出其为正交结构,晶胞参数为a=0.75604 nm,b=1.04823 nm,c=0.72657 nm,空间群为Pnma(62)。在紫外光的激发下,晶体在434 nm左右有一个宽的发射峰,对应于Eu²⁺的4f⁶5d¹→4f⁷跃迁;光致衰减时间1.473μs,晶体在X射线激发下的发光强度随Eu²⁺离子浓度增加而增强。     

大环多胺型荧光探针的研究进展

大环多胺作为含有多个氮原子和闭合环状结构的一类电子供体,在构筑荧光探针方面具有独特的优势。代表性的大环多胺如四氮环(cyclen、cyclam和pyclen)和三氮环(tacn)等,它们被广泛用于金属离子、阴离子、生物活性小分子和生物大分子探针的识别基团或功能基团。本文依据检测对象的不同,综述近年来大环多胺在荧光探针的设计、制备及应用方面的优秀成果,并对未来其在荧光检测分析领域的进一步发展进行了展望。     

价格一致性系统与风险偏好

本文研究了风险偏好问题.利用简单市场模型,讨论了个人风险偏好和市场风险偏好,给出了两种风险偏好的数学定义,该定义具有自然直观的经济学意义.     

无机砷甲基化研究进展

砷是一种生物活性元素。长期接触砷会导致癌症、心脏病、糖尿病等疾病的发生。无机砷甲基化是砷在动物体内的主要代谢方式,被公认为砷元素的解毒过程,因此无机砷甲基化的研究引起了科学家们的广泛关注并取得了重要进展。本文综述了近年来国内外学者及作者研究组在"砷甲基化酶","无机砷甲基化机制"及"无机砷甲基化抑制"等方面的研究进展。     

Influence of Intertube Additional Atoms on Sliding Behaviors of Double-Walled Carbon Nanotube

The effects of intertube additional atoms on the sliding behaviors of double-walled carbon nanotubes(DWCNTs) are investigated using molecular dynamics(MD) simulation method.The interaction between carbon atoms is modeled using the second-generation reactive empirical bond-order potential coupled with the Lennard-Jones potential.The simulations indicate that intertube additional atoms of DWCNT can significantly enhance the load transfer between neighboring tubes of DWCNT.The improvement in load transfer is guaranteed by the addition of intertube atoms which are covalently bonded to the inner and outer tubes of DWCNT.The results also show that the sliding behaviors of DWCNT are strongly dependent of additional atom numbers.The results presented here demonstrate that the superior mechanical properties of DWCNT can be realized by controlling intertube coupling.The general conclusions derived from this work may be of importance in devising high-performance CNT composites.     

D相AlCuCo准晶各向异性热电势的测量

采用激光交流加热的方法测量了D相AlCuCo准晶周期与准周期两个方向的热电势,温度测量区间为300—1200 K.通过测量发现沿周期方向的热电势符号为负,沿准周期方向的热电势符号为正;沿周期方向在1123 K（850 ℃）热电势有一个跳变;在高温区,热电势并不是单调变化的;实验所用方法能比较灵敏地测量材料相变时的温度点. 关键词： AlCuCo准晶 高温 热电势 交流测量法