Efficiencies of 25% have been obtained with 1-cm-diam AlGaAs/GaAs heteroface concentrator solar cells utilizing an ultrathin AlGaAs window layer design. A low specific resistance (<0.005 Ω cm2) Ohmic contact is achieved by direct contact to the p-GaAs active layer. Liquid phase epitaxy has been developed to grow <500-Å thick window layers on large-area (3.3×3.3 cm) GaAs substrates. Four 1-cm-diam cells are produced from each wafer and demonstrate the potential for larger-scale production.
Experimental and theoretical studies are presented for exciton transitions in p-i-n GaAs/AlGaAs multiple coupled-quantum-well structures where each quantum well consists of two identical wells with a thin barrier. Electroabsorption and photocurrent studies are carried out to identify how the excitonic peaks respond to transverse electric fields. With a careful choice of the dimensions of the coupled quantum well, it is seen that the lowest heavy-hole exciton peak moves at a rate ∼2.5 faster than in a square well. Thus strong modulation is obtained at much lower electric fields. The nature of the higher-energy transitions is also studied.
This paper attempts to investigate Hkb Box (A-356 aluminium alloy) manufactured by Gravity Die casting process. Main objective of this research paper is to find the most influencing parameters on hardness of gravity die casting. Taguchi Technique is a powerful and efficient method for optimizing the process, quality and performance output of manufacturing processes. Taguchi's orthogonal array method and S/N Ratio were used for experiments and it was found that Pouring Time and Pouring Temperature are the most influencing parameters to improve hardness. Finally ANOVA was used to confirm the design of experiment.
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