EBIC-Enabled NanoManipulators - Investigating Dislocations in mc-Solar Cells

Abstract

Multicrystalline silicon (mc-Si) solar cells are an important and cost effective technology with a significant role to play in the mix of energy sources required in the future. Recent advances have led to industrial champion cell efficiencies of over 21% [1], however typical industrial cell performance is much lower, in large part due to variability in the distribution of recombination centers between mc-Si wafers. These recombination centers include impurity decorated grain boundaries and dislocations [2, 3], and act to reduce the efficiency of the solar cell by reducing the number of light generated minority carriers which are collected at the p-n junction. As such, an understanding of these defects-the elements which decorate them, their recombination activity and what processes can reduce this activity, is essential if improvements are to be made.

Microscopy of defects in semiconductors

“…Since the dark spots in the CL image appear in the same location of the corresponding EBIC image, they are not caused by carrier escape from the junction but rather non-radiative recombination at defects, possibly clusters of point defects in the MQW region. Other examples for EBIC include the investigation of grain boundaries in silicon [71], stacking faults in 4H-SiC [75], measurement of the diffusion length in GaN [76,77] and -Ga2O3 [78], recombination behaviour of dislocations in bulk GaN [79] and solar cells [80].…”