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Photovoltaic (PV) module reliability issues, due to silicon cell cracking, are gaining more and more attention due to increasing demand for solar power and reduction of cell thickness to reduce cost. Recent reports show significant effect of encapsulation polymer material on cell cracks leading to the idea of tailoring encapsulation materials for more reliable PV modules. This paper investigates the effect of encapsulation modulus on the cell residual stress using Synchrotron scanning X-ray microdiffraction (µSXRD), which has been proven to be an effective technique to probe the stress in silicon solar cells, especially once they are encapsulated. The post lamination residual stress in the encapsulated multi-crystalline silicon (mc-Si) solar cells was reported for the first time using µSXRD in this manuscript and provide quantitative evaluation of the effect of encapsulation modulus on the cell residual stress. Further, simple approximate finite element (FE) model was also developed to evaluate the effect of the encapsulation polymer on the cell stress. The FE simulations predict the trend of the stress variation with encapsulation polymer modulus very well. Dynamic mechanical analysis and rheological testing of the encapsulation polymers was also performed to correlate the polymer behaviour with the experimental and simulated stresses. Both experimental and simulation results show a similar trend of significant cell stress variation with encapsulation polymer modulus. In the case of external loading, the temperature of load application is observed to be very significant as it dictates the elastic state of the encapsulant, leading to critical conclusion that the encapsulant needs to be selected based on elastic behaviour over the temperature history of the encapsulant during module fabrication and operation. The results and discussion presented are expected to be very useful for development of more reliable PV modules.

Abstract: InGaAs channel FinFETs with self-aligned molybdenum (Mo) contacts was demonstrated using a gate-last process. By realizing Mo contacts on in situ doped n++ InGaAs source and drain and self-aligned to channel, the FinFETs achieved series resistance of ∼250Ωμm, which is the lowest value reported-to-date for InGaAs non-planar n-MOSFETs. A FinFET with channel length of 500nm and equivalent oxide thickness (EOT) of 3nm has an on-state/off-state current ratio of ∼105 and peak extrinsic transconductance of 255μS/μm at drain voltage of 0.5V. To further reduce EOT, atomic-layer-deposited HfO2/Al2O3 high-k dielectric was integrated in InGaAs FinFETs. Good interface quality and small EOT of ∼1nm were achieved. Forming gas annealing (FGA) was used for drive current enhancement. A 300°C 30min FGA leads to ∼48% increase in drive current as well as significant reduction of subthreshold swing, probably due to an improvement of the HfO2/Al2O3/InGaAs interface quality. [Copyright &y& Elsevier]

Fourier transform infrared (FTIR) spectroscopy was used to characterize the state of dispersion of layered silicate in polymer nanocomposites. The nanocomposite samples were based on poly(hexamethylene isophthalamide) and montmorillonite nanoclay prepared by melt intercalation. The infrared spectra of SiO stretching bands between 1150 and 960 cm−1 are found to be very sensitive to the extent of nanoclay dispersion at the molecular level. Increased level of nanoclay delamination resulted in significant changes to the out-of-plane a [ABSTRACT FROM AUTHOR]