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Numerical simulation of electron-beam-induced current near a silicon grain boundary and impact of a p-n junction space charge region(2001) Corkish, Richard; Altermatt, Pietro P.; Heiser, GernotJournal ArticleThree-dimensional numerical simulations of electron-beam-induced current (EBIC) near a vertical silicon grain boundary are demonstrated. They are compared with an analytical model which excludes the effect of carrier generation other than in the bulk base region of a solar cell structure. We demonstrate that in a wide range of solar cell structures recombination in the space charge region (SCR) significantly affects the EBIC results and hence needs to be included in the data evaluation. Apart from these findings, simulations of a realistic silicon solar cell structure (thick emitter, field-dependent mobility, etc.) are demonstrated.
(2000) Cotera, Angela; Simpson, John; Erickson, E; Colgan, Sean; Burton, Michael; Allen, DavidJournal Article
Modeling evapotranspiration during SMACEX: Comparing two approaches for local- and regional-scale prediction(2005) Su, H; McCabe, Matthew Francis; Wood, E.F.; Su, Z; Prueger, J.Journal Articlehe Surface Energy Balance System (SEBS) model was developed to estimate land surface fluxes using remotely sensed data and available meteorology. In this study, a dual assessment of SEBS is performed using two independent, high-quality datasets that are collected during the Soil Moisture-Atmosphere Coupling Experiment (SMACEX). The purpose of this comparison is twofold. First, using high-quality local-scale data, model-predicted surface fluxes can be evaluated against in situ observations to determine the accuracy limit at the field scale using SEBS. To accomplish this, SEBS is forced with meteorological data derived from towers distributed throughout the Walnut Creek catchment. Flux measurements from 10 eddy covariance systems positioned on these towers are used to evaluate SEBS over both corn and soybean surfaces. These data allow for an assessment of modeled fluxes during a period of rapid vegetation growth and varied hydrometeorology. Results indicate that SEBS can predict evapotranspiration with accuracies approaching 10%-15% of that of the in situ measurements, effectively capturing the temporal development of surface flux patterns for both corn and soybean, even when the evaporative fraction ranges between 0.50 and 0.90. Second, utilizing high-resolution remote sensing data and operational meteorology, a catchment-scale examination of model performance is undertaken. To extend the field-based assessment of SEBS, information derived from the Landsat Enhanced Thematic Mapper (ETM) and data from the North American Land Data Assimilation System (NLDAS) were combined to determine regional surface energy fluxes for a clear day during the field experiment. Results from this analysis indicate that prediction accuracy was strongly related to crop type, with corn predictions showing improved estimates compared to those of soybean. Although root-mean-square errors were affected by the limited number of samples and one poorly performing soybean site, differences between the mean values of observations and SEBS Landsat-based predictions at the tower sites were approximately 5%. Overall, results from this analysis indicate much potential toward routine prediction of surface heat fluxes using remote sensing data and operational meteorology. © 2005 American Meteorological Society.