Crystalline silicon thin-film solar modules require a cost-effective means
for the fabrication of an integrated series connection. We introduce select
ive epitaxy by ion-assisted deposition through shadow masks for the integra
ted series connection of ultrathin monocrystalline and textured Si solar ce
lls. The series connection is made in situ during Si-film deposition thus a
voiding any trench etching. The open-circuit voltage of an experimental min
i-module consisting of six cells is six times as large as the open-circuit
voltage of a single cell. Epitaxy through shadow masks also permits the in
situ realization of parallel multi-junction solar cells. The experimental q
uantum efficiency analysis of a parallel multi-junction device with three j
unctions reveals an enhanced carrier collection. The apparent effective dif
fusion length of the multi-junction cell is three times larger than that fo
r a conventional single-junction device. (C) 2000 Elsevier Science B.V. All
rights reserved.