铁电效应调控的高性能p-NiO/i-BaTiO_(3)/n-ITO自供能紫外光电探测器

近年来,自供能的紫外光电探测器由于无需任何外部偏压即可工作而成为军事和民用领域的研究热点。其中,钛酸钡(BTO)作为一种宽禁带铁电材料,拥有良好的铁电、压电和热电性能,可以产生本征自发极化场来分离光生载流子,从而实现自供能紫外光电探测。到目前为止,基于BTO的自供能光电探测器已经取得了巨大进展,然而,除了使用高质量的单晶材料外,所报道的器件往往表现出低响应度(10^(-8)~10^(-7) A·W^(-1))。本文利用低成本的射频溅射技术,制造了一种高性能的NiO/BTO/ITO p-i-n异质结构自供能紫外光电探测器。通过将BTO的铁电去极化场和p-i-n结的内建电场耦合,能有效提高光生载流子的分离和迁移。因此,该器件在正极化态下255 nm波长紫外光照射下的响应度可以达到3.4×10^(-5) A·W^(-1),远远高于其他已报道的基于非晶态和陶瓷BTO制备的紫外光电探测器。此外,该器件具有0.3 s/0.4 s的快速响应时间。本工作为提高BTO光电探测器的性能提供了一种新的策略。

Replanting of broadleaved trees alters internal nutrient cycles of native and exotic pines in subtropical plantations of China

Background:The replanting of broadleaved trees in pure coniferous plantations is widely implemented,as mixed plantations are generally more stable and functional.However,the effect of interspecific interactions between broadleaved and coniferous trees on internal nutrient cycles of conifers remains unclear.Methods:We selected pure coniferous plantations of a native(Pinus massoniana)and an exotic(P.elliottii)pine species and their corresponding mixed plantations with broadleaved trees(Schima superba)in subtropical China,and measured the nitrogen(N)and phosphorus(P)contents in the rhizosphere soils,fine roots,twigs,needles and needle litter of pines.We calculated the root capture,needle resorption and translocation of N and P by pines to determine the mobility of nutrients in trees.Results:Although the N and P in the rhizosphere soils increased due to the replanting of broadleaved trees,the N and P contents in the aboveground tissues of the two pine species did not increase in mixed plantations.Mixed planting had a negative effect on the N and P capture of native pine and a positive effect on that of exotic pine.The N and P resorption efficiencies increased in native pine but were unchanged in exotic pine after the replanting of S.superba.Native pine preferentially employed an aboveground nutrient resorption strategy,whereas exotic pine tended to adopt a belowground nutrient capture strategy after replanting.Translocation of N and P in trees was detected,which reflected the trade-offs between root nutrient capture and needle nutrient resorption.Conclusions:The effect of mixed planting varied between the species of native and exotic pines,and the internal nutrient cycles of both pine species might be dominated by interspecific interaction effects on nutrients rather than soil nutrients.Our study highlights the importance of selecting suitable broadleaved species for replanting in coniferous plantations.

Fluorescence and Photosensitizing Behavior of N-(p-Phenoxyphenyl)methacrylamide and Its Polymer

A novel acrylic monomer bearing aromatic ethereality group N-(p -phenoxy-phenyl) methacrylamide(MAPOA) was synthesized and polymerized. The fluorescence spectra of MAPOA and its polymer were studied, showing that the polymer displays a stronger fluorescence than its monomer at the same chromophore concentration. The fluorescence of P(MAPOA) was quenched by adding electron deficiency monomers such as MMA, AN etc .. It is another example of showing the 'fluorescence structural self-quenching effect' as we reported previously, from which it is demonstrated again that this phenomenon is not an accidental one but a common effect for acrylic monomers bearing electon-donating chromophores. The photopolymerization of AN sensitized by MAPOA and P(MAPOA) was studied. The kinetic equation of the polymerization was obtained and represented as follows: R _p∝ 0.38 × 0.78 , R _p∝ 0.33 × 0.71 The overall activation energies were determined to be E_ a =24\^22 kJ/mol(MAPOA) and E_ a =26\^31 kJ/mol respectively. The fluorescence analysis of the resulted P(AN) showed that the sensitizer also entered into the P(AN) chains. A mechanism of the formation of a charge transfer complex and free radical initiation was suggested for the photopolymerization of AN sensitized by MAPOA and P(MAPOA).

The Inhibitory Degree Between Skeletonema costatum and Dinoflagllate Prorocentrum donghaiense at Different Concentrations of Phosphate and Nitrate/Phosphate Ratios

Interactions between Skeletonema costatum (S. costatum) and Prorocentrum donghaiense (P. donghaiiense) were inves-tigated using bi-algal cultures at different concentrations of phosphate (PO4-P) and nitrate/phosphate (N/P) ratios. Experiments were conducted under P-limited conditions and the Lotka-Volterra mathematical model was used to simulate the growth of S. costatum and P. donghaiense in the bi-algal cultures. Both of these two species were inhibited significantly in bi-algal culture. The results of the simulation showed that the inhibitory degree of S. costaum by P. donghaiense was high when the concentration of PO4-P was low (0.1μmolL-1/2 d), but that of P. donghaiense by S. costaum was high with increased PO4-P supply (0.6μmolL-1/2 d). At low concen-tration of PO4-P (0.1μmolL-1/2 d), or high concentration of PO4-P (0.6μmolL-1/2 d) with high N/P ratio (160), the interactions be-tween S. costatum and P. donghaiense were dependent on the initial cell densities of both species. At high concentration of PO4-P (0.6μmolL-1/2 d) with low N/P ratio (25 or 80), S. costatum exhibited a survival strategy superior to that of P. donghaiense. The de-gree of inhibition of P. donghaiense by S. costaum increased with elevated N/P ratio when the medium was supplemented with con-centration 0.1μmolL-1/2 d of PO4-P. The degree of inhibition to P. donghaiense by S. costaum increased with elevated N/P ratio at low concentration of PO4-P (0.1 μmolL-1/2 d). This trend was conversed at high concentration of PO4-P (0.6μmolL-1/2 d). However, the degree of inhibition of S. costaum by P. donghaiense increased with the increased N/P ratio at different PO4-P concentrations (0.1μmolL-1/2 d and 0.6μmolL-1/2 d). These results suggested that both phosphate concentration and N/P ratio affected the competition between S. costaum and P. donghaiense: P. donghaiense is more competitive in environments with low phosphate or high N/P ratio and the influence of N/P ratio on the competition was more significant with lower phosphate concentration.

Synergistic Effect of Nitrogen/Phosphorus Co-Doping and Molybdenum Carbide Induced Electron Redistribution of Carbon Layer to Boost Hydrogen Evolution Reaction

The development of highly efficient non-precious-metal-based electrocatalysts for the hydrogen evolution reaction is imperative for promoting the large-scale application of electrochemical water splitting.Herein,nitrogen/phosphorus co-doped carbon nanorods encapsulated Mo_(2)C nanoparticles(Mo_(2)C@PNc)have been prepared by pre-phosphating treatment in combination of the coordination with polydopamine and the subsequent pyrolysis.The phosphating temperature has a significant effect on the content of phosphorus within the resultant Mo_(2)C@PNC,and the optimal catalyst delivers superior HER activity with the low overpotential of 104 mV at a current density of 10 mAcm^(-2) and good stability for 8 h,which has been theoretically demonstrated to originate from the synergistic effect between P doping and Mo_(2)C induced electron redistribution of nitrogen-doped carbon layer.

Anti-tumor effects of p53N15-based fusion peptide in the transfected H1299 lung cancer cells

Objective Loss-of-function mutation of p53,a tumor suppressor gene,is an important mechanism for the development of human cancers. In this study we tried to transfect p53N15-based fusion peptide into H1299,a lung cancer cell line,and evaluate the anti-tumor effects of the fusion peptide. Methods Adeno-associated virus (AAV) vectors were used for transfecting p53N15 fusion peptide into p53-null lung adenocarcinoma H1299 cells.

Surface Quantum-Dimensional Photocarrier Recombination in CdTe Microcrystals

The scope of the study is the spectra of low-temperature (T = 2K) photoluminescence of a p-CdTe/n-CdS film heterostructure comprising a monolayer of CdTe microcrystals, where a single microcrystalline particle is typically one micron in size. Focus is made on the dominant band of “super-hot” emission appearing in the spectral region located in energy above the fundamental absorption edge of a CdTe bulk crystal. A theoretical model has been developed that assumes the existence of a space-charge layer inside a microcrystal, which leads to the formation of a triangular potential well for an electron near the surface. The anomalous emission band arises as a result of the optical transitions of electrons from near-surface levels of spatial quantization to valence band states.

The Systematics Study of (n, p) Reaction Cross-Sections at 14.7 MeV Neutron Energy

Based on the statistical model and taking into account the Q-value dependence and odd-even effects, we proposed a new empirical formula to reproduce the cross sections of the (n, p) reactions at 14.7 MeV neutron energy and at the target mass number 14 ≤ A ≤ 198 for even A and 29 ≤ A ≤ 205 for odd A. All calculated results from the proposed empirical formula were compared to the experimental data as well as the available semi-empirical formula obtained by other authors. A high level of agreement has been found between the collected experimental data and the most of semiempirical formulae obtained by others.

Double-gate tunnel field-effect transistor:Gate threshold voltage modeling and extraction

The tunnel field-effect transistor(TFET) is a potential candidate for the post-CMOS era.As one of the most important electrical parameters of a device,double gate TFET(DG-TFET) gate threshold voltage was studied.First,a numerical simulation study of transfer characteristic and gate threshold voltage in DG-TFET was reported.Then,a simple analytical model for DG-TFET gate threshold voltage VTG was built by solving quasi-two-dimensional Poisson equation in Si film.The model as a function of the drain voltage,the Si layer thickness,the gate length and the gate dielectric was discussed.It is shown that the proposed model is consistent with the simulation results.This model should be useful for further investigation of performance of circuits containing TFETs.

Two-dimensional threshold voltage model of a nanoscale silicon-on-insulator tunneling field-effect transistor

The tunneling field-effect transistor（TFET） is a potential candidate for the post-CMOS era.In this paper,a threshold voltage model is developed for this new kind of device.First,two-dimensional（2D） models are used to describe the distributions of potential and electric field in the channel and two depletion regions.Then based on the physical definition of threshold voltage for the nanoscale TFET,the threshold voltage model is developed.The accuracy of the proposed model is verified by comparing the calculated results with the 2D device simulation data.It has been demonstrated that the effects of varying the device parameters can easily be investigated using the model presented in this paper.This threshold voltage model provides a valuable reference to TFET device design,simulation,and fabrication.

Photorefractive Effect in an Azobenzene Chromophore Side Groups Polymer

We have analyzed the photorefractive（PR） effect of a polymer composite was reported which combines a novel bi-functional poly（N-vinyl）-3-[p-nitrophenylazo]carbazolyl（PVNPAK） and 2,4,7-trinitro-9-fluorenone（TNF）. PVNPAK was synthesized by a post-azo-coupling reaction, with an azo derivative as the electrooptic chromophore and carbazolyl as photoconductive moiety. The asymmetric two-beam coupling gain of 13.9 cm-1 and diffraction efficiency of 1.2% for poled polymer film fabricated using a corona poling are obtained at the wavelength of 647.1 nm, confirming photorefractivity. We interpreted this result as the orientational enhancement, in which the spatial charge field may enhance the modulated orientation of the azobenzen chromophore. It is unexpected that the photorefractive gain of 9.5 cm-1 for the unpoled polymer film also was observed without external field in two-beam coupling（TBC） experiment. This phenomenon is attributed to a light-induced orientational grating when the azobenzene groups are illuminated by polarized light.

Influence of Deformation on CVC p-n-Junction in a Strong Microwave Field

This paper investigates the current-voltage characteristics (CVC) strain of p-n-junction in a strong microwave (MW) field and shows that the deformation increases the current generated in the p-n-junction. We analyze the current-voltage characteristics of p-n-junction in which three-dimensional space (I,U,e) gives more complete information than the two-dimensional.

N、P、K三要素对水稻产量的效应分析

利用数学模型研究了N、P、K对水稻产量的影响 ,分析了单因素效应、双因素效应和边际效应 ,得出三要素对产量的贡献率大小依次为 :N 1.2 0 81、P 1.0 5 2 7、K 0 .8499;N和P互作明显 ;当P处于高水平时 ,N的增产效果明显。说明高N、P配合适当的K是提高水稻产量的重要途径之一。

硅p-n结太阳电池对DF激光的响应

对硅p n结太阳电池在DF激光辐照下的响应进行了理论和实验研究。推导了p n结反向饱和电流随温度的近似变化关系。根据该近似关系,计算了太阳电池在DF激光辐照过程中输出电压的变化曲线。计算结果和实验结果之间取得了比较好的一致性。

N、P、K肥对香根草修复土壤镉、锌污染效率的影响

通过盆栽试验研究在30 mg/kg镉(Cd)污染土壤条件下N[CO(NH2)2:100、200、300 mg/kg土]、P(P2O5:50、100、200 mg/kg土)和K(KCl:100、200、300 mg/kg土)处理对香根草修复土壤Cd和锌(Zn)污染效率的影响。结果表明:3种N处理能促进香根草地上部生长,而且显著提高地上部特别是叶的Cd和Zn含量,导致其修复效率成倍显著增加;200 mg/kg K处理显著提高Zn修复效率,但300 mg/kg K和50、200 mg/kg P处理却显著降低Cd、Zn修复效率。因此,为改善香根草对较贫瘠土壤中Cd、Zn污染的修复效率,应对香根草适施N肥,并控制或者不施P、K肥为佳。

CuPc-G-PAn/Perylenes异质结太阳电池性能研究

对聚苯胺材料进行染料接枝改性 ,将其用作异质结光伏电池的 p型材料 ,制作出结构为导电玻璃 /酞菁铜接枝聚苯胺 (p型 ) / (n型 ) /Al)简写为 ITO/Cu Pc- G- PAn(p型 ) / (n型 ) /A1 )的有机 p- n异质结光伏电池。该电池在 37.2 W/m2 的碘钨灯照射下 ,开路电压 Voc=80 2 m V,短路电流 Isc=41μA/cm2 ,填充因子 FF =58 ,能量转换效率大约为 0 .51 ,它比聚苯胺及肖特基电池大得多。通过测量其电流—电压 J— V和电容—电压 C— V特性 ,研究了其光伏效应及电学性能。J— V特性表明 ,二极管的曲线因子约为 6.3,比 1大得多 ;C— V特性表明 ,在 Cu Pc- G- PAn/界面处的耗尽层约为 2 31 nm,从 p/n层的光吸收谱可知 ,光激活层在 Cu Pc- G- PAn/界面处 ,它们分别与 ITO及铝形成欧姆接触。

TiO_2/n-Si/p-Si及n-PS/p-PS/Si的光伏特性

在抛光的p型单晶硅上通过扩散工艺制备pn结,采用此种硅片利用阳极腐蚀法制备多孔硅（PS）。用磁控溅射镀膜机在有pn结的单晶硅表面镀上一层TiO2纳米结构薄膜,并用表面光电压谱（SPS）研究了n-PS/p-PS/Si和TiO2/n-Si/p-Si的表面光伏特性。结果表明TiO2/n-Si/p-Si和n-PS/p-PS/Si的光伏效应比n-Si/p-Si在不同程度上有所提高。在300～600℃热处理温度范围内TiO2/n-Si/p-Si的光伏效应随温度的升高而增强,600～800℃范围内随温度的升高而降低。

飞秒激光诱发硅PIN光电二极管饱和特性的实验研究(英文)

实验研究了不同脉冲能量的飞秒激光诱发硅PIN光电二极管瞬态响应信号的特性。发现探测器响应瞬态响应信号相继出现了三个明显的相位,深入讨论了飞秒激光诱发的高注入载流子在瞬态响应信号演化过程中所起的作用。结果表明,高注入载流子产生的空间电荷屏蔽效应是导致瞬态响应信号呈现三个相位的主要因素,它导致瞬态响应信号的持续时间主要取决于载流子双极扩散的速度。增加飞秒激光的脉冲能量会进一步延长探测器瞬态响应信号的持续时间。因此,飞秒激光会削弱探测器的工作性能,尤其是在高速信号探测中的工作性能。

一种新型P-N-Cl协效阻燃剂的合成及其在热固性树脂中的应用

以邻苯二胺、顺丁烯二酸和三氯氧磷为原料,以三乙胺作为缚酸催化剂,合成了新型P-N-Cl协效苯并咪唑型阻燃剂。利用元素分析、FTIR及1H NMR波谱对中间体和阻燃剂分子结构进行了表征。通过单因素实验考察了反应时间、反应温度及原料物质的量比nPOCl3∶n中间体(I)等主要反应条件对P-N-Cl协效阻燃剂收率的影响,发现在t=8 h,T=75℃以及nPOCl3∶n中间体(I)=2.25的优化条件下,阻燃剂最大收率为73.6%。通过极限氧指数(LOI)测定,考察了该P-N-Cl协效阻燃剂对191型不饱和树脂和环氧树脂E-44的阻燃效果,结果发现在阻燃剂质量分数12%时二者的LOI可分别达到33.7%和32.3%,表明其具有良好的阻燃性能和潜在应用前景。