纳米硅薄膜光吸收谱的研究

用恒定光电导法测量了纳米硅(其晶粒尺寸为3-5nm,晶态成分比X_c为45％—50％)薄膜在0.9—2.5eV范围的光吸收谱。分析了在不同光子能量范围可能存在的对光电导作主要贡献的几种光跃迁过程,以及随着X_c的增加,材料由非晶、微晶转变为纳米硅薄膜时光吸收谱的变化。发现纳米硅晶粒之间的界面区(平均厚度约为1nm)中载流子的跃迁及传输过程对整个范围的光吸收谱起主导作用。联系纳米硅的这种特殊结构解释了有关实验结果。 关键词：     

An Application of the Method of Lines to Multidimensional Free Boundary Problems

Multidimensional free boundary problems for elliptic and parabolicdifferential equations, among them one phase Stefan problems,are partially discretized with the method of lines. The multi-pointfree boundary problem for the resulting system of second orderordinary differential equations is solved iteratively with anSOR type iteration. At each step of this iteration a free boundaryproblem for a single ordinary differential equation must besolved for which an initial value technique is used. The methodcan effectively cope with quite general space and time dependentfree surface conditions.     

Modified Damped Least Squares: An Algorithm for Non-linear Estimation

A new method for non-linear regression is described and comparedto three other well-known methods for the non-linear least squaresproblem. Convergence theorems and computational results aregiven which indicate that the new method is more efficient andreliable than previously published methods.     

ChemInform Abstract: Bonding,Structure, and Stability of Ternary Hydrides A2MH2 (A: Li,Na; M: Pd,Pt).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

An outdoor investigation of the absorption degradation of single-junction amorphous silicon photovoltaic module due to localized heat/hot spot formation

This paper investigates the absorbance degradation of single-junction amorphous silicon (a-Si:H) photovoltaic (PV) module, due to the presence of localized heat. The decrease in optical density is a huge challenge due to the long-term degradation of PV modules. The reduction in solar cell optical density causes a decline in its conversion efficiency. This decreases the photogenerating current, hence reduces the effective efficiency of the PV device. An infrared thermography was used for mapping the module temperature profile. Fourier transform infrared spectroscopy (FTIR) was used for the absorption characterization. The rationale behind the outdoor deployment was to deduce a practical effect of hot spot formation on the module’s absorption ability. The results show a direct correlation between localized heat and the absorption degradation.