(Georgia Institute of Technology, 2005-01)
Meemongkolkiat, Vichai; Nakayashiki, Kenta; Rohatgi, Ajeet; Crabtree, Geoffrey; Nickerson, Jeff; Jester, Theresa L.
A systematic study of the variation in resistivity and lifetime on cell performance, before and after light-induced
degradation (LID), was performed along the B- and Ga-doped Czochralski (Cz) ingots. Screen-printed solar cells with Al-back surface field were fabricated and analyzed
from different locations on the ingots. Despite the large variation in resistivity (0.57 Ω-cm to 2.5 Ω-cm) and lifetime
(100-1000 μs) in the Ga-doped Cz ingot, the efficiency variation was found to be ≤ 0.5%. No LID was observed in the cells fabricated from the Ga-doped ingot. In contrast
with the Ga-doped ingot, the B-doped ingot showed a very tight resistivity range (0.87 Ω-cm to 1.22 Ω-cm), resulting in very tight lifetime and efficiency distributions. However, the LID effect reduced the efficiency of these B-doped cells by about 1.1% absolute. Additionally, the use of
thinner substrate and higher resistivity B-doped Cz is shown to effectively reduce the LID effect.