Programm Photovoltaik Ausgabe 2009 ... - Bundesamt für Energie BFE

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Results
Microstructure characterizations of the Si thin film by EBSD:
The preliminary results show that the combined laser-crystallization- SPE process successfully produced
grains of several 10�m wide and more than several 100�m long (Fig. 2). The grain shape is
anisotropic, elongated in the direction of the laser path. The smaller grains are located at the border of
the trace at the rim of the melt pool and the larger grains are in the middle of the trace in the hotter
region. Laser path overlaps allow to remelt the smaller grains at the rim of the previous path. Grain
growth of the second raw occurs by lateral epitaxial solidification from the grains of the previous raw.
The grain boundary population is dominated by twin boundaries of first (�= 3) and second order
(� = 9). The first order twin boundaries are largely dominant forming 30-50% of the total boundaries.
� = 9 can form 5 -10% of the total boundaries and � = 27 (third order twin boundaries) can be relatively
abundant, forming 1-8% of the boundaries population. Low angle boundaries ( 15°; red lines: �3, 60° rotation
around axis; green lines: �9, 38.9° rotation around axis. CLS boundaries dominate
the grain boundary population of the samples.
c) Low (< 15°) and high angle boundaries map without the twins.
d) Intergranular misorientation gradient map. Strong progressive lattice bending inside the
grains is observed.
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Large grained, low stress multi-crystalline silicon thin film solar cells on glass by a novel combined diode laser and solid phase crystallization process, X. Maeder, Empa