Influence of SiNx:H film properties according to gas mixture ratios for crystalline silicon solar cells

The Hydrogenated silicon nitride (SiN_x:H) using plasma enhanced chemical vapor deposition is widely used in photovoltaic industry as an antireflection coating and passivation layer. In the high temperature firing process, the SiN_x:H film should not change the properties for its use as high quality surface layer in crystalline silicon solar cells. For optimizing surface layer in crystalline silicon solar cells, by varying gas mixture ratios (SiH₄ + NH₃ + N₂, SiH₄ + NH₃, SiH₄ + N₂), the hydrogenated silicon nitride films were analyzed for its antireflection and surface passivation (electrical and chemical) properties. The film deposited with the gas mixture of SiH₄ + NH₃ + N₂ showed the best properties in before and after firing process conditions.The single crystalline silicon solar cells fabricated according to optimized gas mixture condition (SiH₄ + NH₃ + N₂) on large area substrate of size 156 mm × 156 mm (Pseudo square) was found to have the conversion efficiency as high as 17.2%. The reason for the high efficiency using SiH₄ + NH₃ + N₂ is because of the good optical transmittance and passivation properties. Optimized hydrogenated silicon nitride surface layer and high efficiency crystalline silicon solar cells fabrication sequence has also been explained in this study.     

Electronic linewidth narrowing method for single axial mode operation of Q-switched Nd: YAG lasers

Electronic control of the Q-switch is used to obtain single axial mode output from an unstable resonator Nd: YAG oscillator. Controlled opening of the Q-switch following prespiking pulses provides over 10 MW of peak power in a single axial mode without significant output power reduction.     

Congruential Inventory Model for Two-Echelon Distribution Systems

Large-scale inventory-distribution systems typically comprise a hierarchy of warehouses that stock goods for distribution to retailers at which demand for these goods originates. This paper develops an inventory model for two-echelon distribution systems under the assumption that the central warehouse and retailers order periodically. Characteristics of the optimal policy are described. An iterative solution procedure is presented to find optimal or near optimal operating-policy variables. Solutions of the model to a large number of test examples show that the model outperforms other existing models in the literature without sacrificing the computation time. Tested against the lower bounds on the optimal average annual variable cost obtained by removing some of the ordering costs, the solutions of the present model are found to be near optimal.     

A shock-tube measurement of the SiO(E1Σ+ − X1Σ+) transition moment

The sum of the squares of the electronic transition moments, Σ|R_e|², for the E¹Σ⁺ ?X¹Σ⁺ band system of SiO has been determined from absorption measurements conducted in the reflected-shock region of a shock tube. The test gas was produced by shock-heating a mixture of SiCl₄, N₂O and Ar, and the spectra were recorded photographically in the 150–230 nm wavelength range. The values of the Σ|R_e|² were determined by comparing the measured absorption spectra with those produced by a line-be-line synthetic spectrum calculation. The value of the Σ|R_e|² so deduced at an r-centroid value of 3.0 Bohr was 0.86±0.10 atomic units.