From polycrystalline to single crystalline silicon on glass

Thin film transistors and solar cells from polycrystalline silicon suffer from the influence of grain boundary charges. This contribution reviews three possibilities to suppress these charges: (i) by the selection of specially oriented grain boundaries in small-grained silicon. Analysis of solar cells demonstrates that (110)-textured films must contain electrically low-active boundaries. (ii) Special laser crystallization yields large-grained Si of excellent quality. (iii) Transfer techniques allow one to fabricate single crystal films on foreign substrates. In addition to these three methods, we discuss joined-wafer silicon for growth of single crystalline Si films and layers of essentially unlimited size.