Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Absorber layers consisting of nanostructured Si are candidates for next generation thin film Si solar cells. For this aim, Si-SiO2 nanocomposites with crystalline sponge-like Si are promising materials since their band gap is increased by quantum confinement and since they provide electrical interconnectivity. Such nanosilicon has recently been fabricated by annealing of non-reactively sputter deposited SiOx films (x< 1). It is formed by solid state phase separation into a percolated network of Si nanowires. The phase separation is usually accompanied by crystallization of Si. Here, SiOx layers have been grown by ion beam sputter (IBS) as well as by reactive magnetron sputter (RMS) deposition. Formation of sponge-like Si-SiO2 nanocomposites has been achieved for the IBS deposited layers by scanning with a diode laser line source (LIMO GmbH) and furnace treatment. Laser processing leads to morphologies self-similar to furnace annealed samples, but scaled up by a factor of ~10. Moreover, the laser process proceeds approximately 106 times faster. The larger mean structure size for the shorter process is explained by a phase separation in the liquid state in contrast to a solid state process which has been observed for furnace annealing. Furthermore, filament-like morphologies produced by RMS deposition and furnace annealing are compared to those of the IBS deposited layers.