Efficient methods for detection of SiC and Si3N4 precipitates and filaments in multi-crystalline silicon wafers and solar cells

Two easy and efficient methods are demonstrated to detect SiC and Si3N4 filaments and precipitates in multi-crystalline silicon (mc-Si) wafers and solar cells by Optical Light (OLM) Microscopy and Scanning Electron Microscopy (SEM). In the case of OLM the image is created in the dark field mode which clearly visualizes the grain boundaries decorated by filaments in acidic etched silicon solar cells. In the case of SEM the image is created by a combination of Secondary Electrons (SE) imaging and Back Scattered Electrons (BSE) imaging. By using this method a clear discrimination of precipitates with different chemical compositions is possible. Note that both methods make it possible to investigate and analyze relatively large sample areas in a comparatively short period of time.