INVESTIGATIONS ON DIFFERENT TYPES OF FILAMENTS IN MULTI-CRYSTALLINE SILICON FOR SOLAR CELLS

摘要

Highly conductive SiC filaments may short-circuit the emitter and the back contact of a silicon solarcell. The appearing severe ohmic shunts may reduce the efficiency of a solar cell and lead to hot spots. Recentinvestigations have shown that there are filaments, which have quite different properties than the well-known highlyconducting filaments. In contrast to the latter, these filaments are non-conducting. We perform differentinvestigations on the different types of filaments to reveal their electrical properties and their nature. By measuringthe current-voltage characteristics we examine the electric properties of the filaments. Scanning electron microscopyand transmission electron microscopy investigations were performed on the filaments to find out their nature. We findthat the conducting filaments indeed consist of cubic silicon carbide. The non-conducting filaments, however, consistof silicon nitride, which was proven by electron energy loss spectroscopy and electron diffraction investigations.