Ultrahigh-Crystalline-Quality Silicon Pillars Formed by Millimeter-Wave Annealing of Amorphous Silicon on Glass

Unique 3D silicon pillar structures that were formed by millisecond-long single-pulse annealing of 110 GHz millimeter-wave radiation incident upon intrinsic-amorphous silicon (a-Si) thin films deposited on glass by hot-wire chemical vapor deposition (HWCVD) were investigated. SiO₂/glass samples were annealed with a millimeter-wave power density of approximately 40kW cm^-2 and a pulse length that varied from 1 to 8.5 ms. The microscopic images show that the pillars have a very high crystallinity without structural defects. The Si pillar is also found to be covered by a thin a-SiO₂ of 80 nm and a relatively thick nc-Si of 950 nm layers on the top and a thin nc-Si layer of 120 nm and a thick SiO₂ layer on the sides. The melt Si pillars are found to retain the egg-like shapes after they crystallize due to high cooling rates.