Improvement of amorphous silicon n-i-p solar cells by incorporating double-layer hydrogenated nanocrystalline silicon structure

We develop a double-layer p-type hydrogenated nanocrystalline silicon (p-nc-Si:H) structure consisting of a low hydrogen diluted i/p buffer layer and a high hydrogen diluted p-layer to improve the hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells. The electrical, optical and structural properties of p-nc-Si:H films with different hydrogen dilution ratio (R_H) are investigated. High conductivity, low activation energy and wide band gap are achieved for the thin films. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) analyses indicate that the thin films contain nanocrystallites with grain size around 3-5 nm embedded in the amorphous silicon matrix. By inserting a p-nc-Si:H buffer layer at the i/p interface, the overall performance of the solar cell is improved significantly compared to the bufferless cell. The improvement is correlated with the reduction of the density of defect states at the i/p interface.     

电极形状对GaN基发光二极管芯片性能的影响

采用Crosslight APSYS这一行业专业软件对p-GaN,InGaN/InGaN多量子阱,n-GaN和蓝宝石的芯片结构研究了不同电极形状与器件的光电性能之间的关系.优化设计了普通指形电极、对称型指形电极、h形指形电极、旋转形电极、中心环绕形电极、树形电极等6种电极结构.通过电极优化设计,电流分布更加均匀,减小了电流的聚集效应.优化后的电极结构结果表明:芯片的电特性得到了提高,芯片的光特性得到了明显改善,芯片的出光效率大幅度提高,芯片的转化效率得到了提升.     

ZnSe相变、电子结构的第一性原理计算

基于第一性原理平面波赝势(PWP)和广义梯度近似(GGA)方法,对闪锌矿结构(ZB)和岩盐结构(RS)的ZnSe在0—20GPa高压下的几何结构、态密度、能带结构进行了计算研究,分析了闪锌矿结构ZnSe和岩盐结构ZnSe的几何结构.在此基础上,研究了ZnSe的结构相变、弹性常数、成键情况以及相变压强下电子结构的变化机理.结果发现:通过焓相等原理得到的ZB相到RS相的相变压强为15.3GPa,而由弹性常数判据得到的相变压强为11.52GPa,但在9.5GPa左右并没有发现简单立方相的出现;在结构相变过程中,sp3轨道杂化现象并未消除,Zn原子的4s电子在RS相ZnSe的导电性中起主要贡献.     

脉冲激光偏振方向对氧分子高次谐波的影响——基于含时密度泛函理论的模拟

采用含时密度泛函方法,结合赝势模型和电子交换相关作用的广义梯度近似,模拟了氧分子在超强飞秒激光脉冲作用下的高次谐波产生现象,并研究了激光脉冲偏振方向对氧分子高次谐波的影响.结果表明氧分子的高次谐波谱具有典型原子谐波谱的特征;当θ=45°(激光偏振方向与分子轴向夹角)时,谐波谱强度最大.这与文献报道的实验结果基本一致.     

移动Ad Hoc网络动力学同步能力的研究

研究了移动Ad Hoc网络的动力学同步行为.用特征值比R来衡量网络的同步能力,特征值比R越小,同步能力越强.结果表明最初该网络的特征值比R随聚类系数C的增加而增加,继续增大聚类系数,特征值比反而减小.特征值比随聚类系数并不是普遍的正比关系也不是反比关系,而是先增大后减小,明显存在一个极值.     

化学发光法测定甲萘威

在NaOH介质中,铁氰化钾氧化鲁米诺产生化学发光,甲萘威对该发光反应有较强的抑制作用且抑制发光强度与甲萘威的浓度呈较好的线性关系,基于此性质建立了测定甲萘威的新方法。在实验的优化条件下,测定甲萘威的检出限为5.5×10-11mol.L-1,线性范围为1.5×10-10—4.0×10-8mol.L-1,对5.0×10-9mol.L-1甲萘威进行了11次平行测定,其RSD为1.74%。该法用于合成样品中甲萘威的测定,结果令人满意。     

换个角度看近地人造卫星的运动

将卫星的近地轨道运动等效为无阻力条件下物体沿地球内两相互垂直的直径轨道的简谐振动的合运动,从而解释了它们的运动周期相同这一事实.     

Effects of fractal gating of potassium channels on neuronal behaviours

The classical model of voltage-gated ion channels assumes that according to a Markov process ion channels switch among a small number of states without memory, but a bunch of experimental papers show that some ion channels exhibit significant memory effects, and this memory effects can take the form of kinetic rate constant that is fractal. Obviously the gating character of ion channels will affect generation and propagation of action potentials, furthermore, affect generation, coding and propagation of neural information. However, there is little previous research on this series of interesting issues. This paper investigates effects of fractal gating of potassium channel subunits switching from closed state to open state on neuronal behaviours. The obtained results show that fractal gating of potassium channel subunits switching from closed state to open state has important effects on neuronal behaviours, increases excitability, rest potential and spiking frequency of the neuronal membrane, and decreases threshold voltage and threshold injected current of the neuronal membrane. So fractal gating of potassium channel subunits switching from closed state to open state can improve the sensitivity of the neuronal membrane, and enlarge the encoded strength of neural information.     

Structure, room-temperature magnetic and optical properties of Mn-doped TiO2 nano powders prepared by the sol-gel process

TiO 2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process,and were annealed at 500 C and 800 C in air for 2 hrs.X-ray diffraction (XRD) measurements indicate that the Mn-TiO 2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 C are of pure anatase and rutile,respectively.The scanning electron microscope (SEM) observations reveal that the crystal grain size increases with the annealing temperature,and the high resolution transmission electron microscopy (HRTEM) investigations further indicate that the samples are well crystallized,confirming that Mn has doped into the TiO 2 crystal lattice effectively.The room temperature ferromagnetism,which could be explained within the scope of the bound magnetic polaron (BMP) theory,is detected in the Mn-TiO 2 samples with Mn concentration of 2 at%,and the magnetization of the powders annealed at 500 C is stronger than that of the sample treated at 800 C.The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO 2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.     

First measurement of the 2H(6He,7Li)n angular distribution and proton spectroscopic factor in 7Li

The angular distribution of the ²H ( ⁶He,⁷Li n reaction was measured with a secondary ⁶He beam of 36.4MeV for the first time. The proton spectroscopic factor of ⁷Li ground state was extracted to be 0.42±0.06 by normalizing the calculational differential cross-sections with the distorted-wave Born approximation to the experimental data. It was discussed that the uncertainty of extracted spectroscopic factors from the one-nucleon transfer reactions induced by deuteron might be reduced by determining the volume integrals of imaginary optical potentials precisely.