Ultra-high material-quality silicon pillars on glass

We investigated a unique crystalline silicon structure-silicon pillars-formed by melt crystallization using millisecond-long single-pulse pulses of 110-GHz radiation of amorphous Si thin films deposited on glass by hot-wire chemical vapor deposition. With many microscopy techniques, we found that these pillars usually contain 1-4 randomly oriented grains with growth direction and grain boundaries perpendicular to the substrate surface. The grains in the Si pillars have ultra-high crystalline quality with grain sizes up to 20 m. We attribute the formation mechanism of the Si pillars to the extremely high heating/cooling rates of Si on a glass substrate using millimeter-wave radiation and the important roles played by wetting and capping layers during the annealing process. Such understandings may enable us to prepare ultra-high-quality, large-grained poly-Si on inexpensive foreign substrates at large scale and low cost.