Current loss in edge-defined film-fed growth silicon

This paper discusses work that has been done to characterize the sources of current loss in edge-defined film-fed growth Si. The authors begin with a model of current generation in a polycrystalline Si solar cell. The model allows one to describe the spatial inhomogeneity of the solar cell caused by the different grains and their varying concentrations of dislocations. The authors then mathematically define the current loss such that it can be quantitatively determined by a spectral response measurement. The authors perform spectral response on a standard edge-defined film-fed growth Si solar cell and measure the current loss. They then perform spatially resolved spectral response on the same solar cell. This technique measures the spectral response of an area 0.5 mm in diameter, allowing mapping of the inhomogeneous spectral response of polycrystalline Si solar cells. The spatially resolved spectral response measurement also allows one to determine the current losses. The authors compare the current loss measured by both spectral response methods and find that they are the same, which validates the model. The authors then measure the electron beam induced current on the same solar cell and show that the current loss is greatest in grains which contain a high concentration of dislocations. They conclude by discussing the two main microscopic causes of the current loss. These losses are predominately intragranular and are not associated with grain boundaries