Defect mapping in full-size multi-crystalline Si wafers

¹ University of South Florida, 4202 E Fowler Avenue, Tampa, Florida, 33620, USA
² National Renewable Energy Laboratory, Golden CO, USA

Corresponding author: Ostapenk@eng.usf.edu

Received: 20 June 2003
Accepted: 28 January 2004
Published online: 15 July 2004

Abstract

Application of scanning techniques is strongly required for in-line/off-line diagnostics of semiconductors with spatial inhomogeneity of electronic properties due to uneven defect distribution. The defect mapping allows performing an initial screening and follow-up local analyses in large-scale materials and devices for electronic applications. This approach is illustrated on multi-crystalline silicon (mc-Si) wafers for solar cells. Four different mapping techniques were applied concurrently to full-size as-grown and processed mc-Si. They include the mapping of (1) minority carrier lifetime, (2) room-temperature photoluminescence, (3) dislocation density, and (4) temperature dependent EBIC and cathodoluminescence. Analyses revealed a clear correlation between the “defect” PL band intensity with the maximum at about 0.8 eV and concentration of the dislocations contaminated by impurities and defects. The 0.8 eV band has a distinctive location at wafer areas with reduced minority carrier lifetime, i.e. regions with enhanced recombination activity of defects. It is demonstrated that the concentration of the 0.8 eV defects has analytical relation to the concentration of non-radiative defects in dislocated regions. The model of these defects is discussed.