Study on subgrain boundaries in cast monocrystalline silicon

Abstract

Cast monocrystalline silicon (mono-Si), also known as quasi-mono-Si, has been recognized for its potential as a high-performance crystalline silicon material due to its low manufacturing costs and high crystal quality. This study investigated the occurrence of high-density dislocation loops in cast mono-Si, which exhibited grid-like propagation caused mostly by subgrain boundaries. The study looked at the fundamental properties of these subgrain boundaries as well as the mechanisms that allow them to propagate in a grid-like pattern within cast mono-Si. Observations revealed differences in the crystallographic misorientation of subgrain boundaries across the ingot, ranging from 1 to 3°. Electron Beam Induced Current (EBIC) tests revealed strong recombination activity at these boundaries under typical conditions. As the temperature gradually decreases from 300 K to 80 K during EBIC testing, subgrain boundaries with shallower energy states emerge, which become more apparent in photoluminescence (PL) tests conducted on Si wafers cut from different heights of the ingot.