Synthesis of the wheat-like CdSe/CdTe thin film heterojunction and their photovoltaic applications

We report on the fabrication of wheat-like CdSe/CdTe thin film heterojunction solar cells made using a simple electrochemical deposition method and close-spaced sublimation technology on indium tin oxide (ITO) substrates. Structural, optical, and electrical properties of the wheat-like CdSe/CdTe thin film junctions were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive spectrometry (EDS), ultraviolet–visible (UV–vis) absorption spectrum and Keithley 2400 analysis. A significant red-shift of the absorption edge is observed in this heterojunction. The heterostructure is composed of the wheat-like CdSe array and CdTe thin film, showing optical properties typical of type II heterostructures that are suited for photovoltaic applications. A photocurrent density of 8.34 mA/cm² has been obtained under visible light illumination of 100 mW/cm². This study demonstrates that the electrochemical deposition and the close-spaced sublimation technology, which are easily adapted to other chemical systems, are promising techniques for large-scale fabrication of low-cost heterojunction solar cells.     

Effects of controllable process factors on Al rear surface bumps in Si solar cells

High efficiency solar cells require good back surface field passivation and high back reflectance in the rear Al region. In module processes, wafer-based solar cell can break through stress during soldering uneven rear aluminum surfaces - a serious problem that affects throughput. This work examined rear surfaces with respect to controllable process factors such as ramping and cooling rates during rapid thermal processing, and the fineness of aluminum powder used in the screen-printed paste. A faster ramp up rate resulted in a uniform temperature gradient between the aluminum and silicon surfaces. As a results, the bumps on the aluminum surface were small and of high density. Fine aluminum metal powder in the paste for screen-printing contact points resulted in large distribution, high density bumps. Bumps formed during cooling in metallization, their sizes and densities were dependent the on uniformity of the aluminum and silicon liquid wetting of the silicon surface.     

Electromagnetic design of the spectrometer section of the KATRIN experiment

The aim of the KATRIN experiment is to determine the neutrino mass directly, with a sensitivity of 0.2 eV (90% CL). KATRIN is located at KIT (Karlsruhe Institute of Technology) and is currently under construction (J. Angrik et al., 2004 [3]).The experiment will analyze the shape of the tritium β-spectrum in the region of the tritium endpoint. A nonzero neutrino mass reduces the maximal energy of the electron and changes the shape of the tritium spectrum, especially close to the endpoint. To reach the sensitivity KATRIN is aiming for, an high energy resolution as well as high statistics and low background are needed. In order to achieve this, KATRIN uses the MAC-E-Filter (Magnetic Adiabatic Collimation followed by Electrostatic Filter) principle, and several background reduction mechanisms. The optimization of both MAC-E-Filter and background reduction is the main challenge of the electromagnetic design. This article describes how these issues are tackled and discusses the actual realization of two major electromagnetic design components.     

本科生分子生物学实验教改中存在的问题及对策

作者结合自己分子生物学实验教学经验,介绍了教研室本科生分子生物学实验教学改革现状,肯定了实验教学改革效果,同时对改革中存在的问题进行深入分析,并提出相应对策。     

LOCALLY STABILIZED FINITE ELEMENT METHOD FOR STOKES PROBLEM WITH NONLINEAR SLIP BOUNDARY CONDITIONS

Based on the low-order conforming finite element subspace （Vh, Mh） such as the P1-P0 triangle element or the Q1-P0 quadrilateral element, the locally stabilized finite element method for the Stokes problem with nonlinear slip boundary conditions is investigated in this paper. For this class of nonlinear slip boundary conditions including the subdifferential property, the weak variational formulation associated with the Stokes problem is an variational inequality. Since （Vh, Mh） does not satisfy the discrete inf-sup conditions, a macroelement condition is introduced for constructing the locally stabilized formulation such that the stability of （Vh, Mh） is established. Under these conditions, we obtain the H1 and L2 error estimates for the numerical solutions.     

The GSI oscillation mystery

In this talk, a short discussion of the GSI anomaly is given. We discuss the physics involved using a comparison with pion decay, and explain why the observed oscillations cannot be caused by standard neutrino mixing.     

基于网络环境下自主学习问题的解决对策研究

本文在自主学习的详细分解研究基础上，通过对网络环境下的自主学习方式的解析，阐述了自主学习的内涵和特征，总结了网络环境下中学生自主学习过程中存在的问题，并给出了相应的解决建议，进而提高我国大学生自主学习的能力。     

细胞挤入狭缝的润滑理论分析

血细胞的入口阻力构成血液循环外周阻力的重要组成部分。本文首次提出一个简化的力学模型,试图探讨细胞挤入二维狭缝的运动特性。本模型的细胞外形根据显微录相设为已知,细胞膜沿其表面滑移。对膜与缝壁间的薄血浆层应用润滑理论,算出压力和剪应力分布,给出了细胞所受阻力。本文得到的细胞运动规律,与显微录相定性一致地模拟了细胞的入口过程。     

非晶硅PIN太阳能电池在强光照射下的光电转换现象

用两种不同波长、不同功率的单色光作为激发光源,研究非晶硅PIN太阳能电池的光电特性,测试并计算了有关数据,发现在高功率强光照射下,PIN太阳电池光电转换呈现一种异常的现象,对此作了理论解释。     

运用状态调节器配置控制系统的极点

本文对线性系统极点配置和状态调节器设计间的关系进行了探讨。在单输入系统中,定义了表明P、Q矩阵和原系统参数及所配置极点间关系的Pc阵列和Qc陈列,导出运用状态调节器对系统进行极点配置的充要条件。在一定程度上,允许时方便地扩展到多输入系统。