12 research outputs found
Multidimensional simulation of hydrogen distribution and turbulent combustion in severe accidents
Time evolution of surface defect states in hydrogenated amorphous silicon studied by photothermal and photocurrent spectroscopy and optical simulation
The time evolution of surface defect density and width of space charge region in thin layer of amorphous silicon is observed experimentally by Fourier transform photocurrent spectroscopy. This work reviews the assumption that photocurrent is insensitive to surface defects for samples thinner than 1500 nm. We show that correct evaluation based on simple optical model comprising layers representing surface defects and layers representing space charge region with reduced collection allows obtaining the same results as from photothermal deflection spectroscopy. Our main approach is the comparison of photocurrent or photothermal deflection spectra measured in absorptance/transmittance mode from layer and substrate side of the thin film. (C) 2011 Elsevier B.V. All rights reserved
Effect of Rough ZnO Layers in Improving Performances of Microcrystalline Silicon Solar Cell
A Method for Efficient Transmittance Spectrum Prediction of Transparent Composite Electrodes
Absorption enhancement of an amorphous Si solar cell through surface plasmon-induced scattering with metal nanoparticles
Optical and structural properties of thin films precipitated from the sol of silicon nanoparticles
Characterization of microcrystalline silicon thin film solar cells prepared by high working pressure plasma-enhanced chemical vapor deposition
Effect of Substrate Morphology Slope Distributions on Light Scattering, nc-Si:H Film Growth, and Solar Cell Performance
Thin-film silicon solar cells are often deposited on textured ZnO substrates. The solar-cell performance is strongly correlated to the substrate morphology, as this morphology determines light scattering, defective-region formation, and crystalline growth of hydrogenated nanocrystalline silicon (nc-Si:H). Our objective is to gain deeper insight in these correlations using the slope distribution, rms roughness (σrms) and correlation length (lc) of textured substrates. A wide range of surface morphologies was obtained by Ar plasma treatment and wet etching of textured and flat-as-deposited ZnO substrates. The σrms, lc and slope distribution were deduced from AFM scans. Especially, the slope distribution of substrates was represented in an efficient way that light scattering and film growth direction can be more directly estimated at the same time. We observed that besides a high σrms, a high slope angle is beneficial to obtain high haze and scattering of light at larger angles, resulting in higher short-circuit current density of nc-Si:H solar cells. However, a high slope angle can also promote the creation of defective regions in nc-Si:H films grown on the substrate. It is also found that the crystalline fraction of nc-Si:H solar cells has a stronger correlation with the slope distributions than with σrms of substrates. In this study, we successfully correlate all these observations with the solar-cell performance by using the slope distribution of substrates