Influence of Localized Structural Defects on the PN Junction Properties

Abstract

Local defects, as micro-fractures, precipitates and other material inhomogeneities in solar cell structure, evidently modify electrical and photoelectrical behavior of the latter. To improve the efficiency and lifetime of existing solar cells, it is important to localize these defects which influence the p-n properties, and assign them corresponding electrical characteristics. Although the electric breakdown can be evident in current-voltage plot, the localization of local defects in the sample, that generate this breakdown, is not so easy task. It has to be done by microscopic investigations and measurement of light emission from defects under electrical bias conditions. Thus to contribute to this end, the structure of defects is microscopically investigated and consequently, the defects can be removed by focused ion beam milling. The experimental results obtained from samples before and after milling are also discussed.