CRYSTALLIZATION IN FLUORINATED AND HYDROGENATED AMORPHOUS-SILICON THIN-FILMS

The amorphous-to-crystalline (AC) transition of amorphous Si thin film s containing fluorine or hydrogen is studied by transmission electron microscopy. The AC transition can be described quantitatively by the i ncubation time prior to the onset of crystallization t0. This paramete r is found to decrease exponentially with temperature with an activati on energy of 1.7 eV for a-Si:F and 3.1 eV for a-Si:H:D. It is found th at during the crystallization process in a-Si:F the crystallites organ ize as dendrite single crystals oriented along the [110] axis perpendi cularly to the film surface. a-Si samples that had been covered by Pd or Al crystallize at appreciably lower temperatures. In the case of Al lower activation energies of 0.7 eV for hydrogenated and 0.4 eV for f luorinated a-Si are measured. In the case of Pd/a - Si:H,F for both ki nds of a-Si an activation energy of 1.7 eV is found.