FORMATION OF POLYCRYSTALLINE SILICON GRAINS IN SI+-PREAMORPHIZED, BF-2+-IMPLANTED (111)SI

[[abstract]]The regrowth of Si+ -preamorphized and BF2+ -implanted thin films on (111)Si has been studied by both plan-view and cross-sectional transmission electron microscopy. Polycrystalline Si grains were found to form in Si+ -preamorphized and BF2+ -implanted (111) Si with the original amorphous -crystalline (a-c) interface located deeper in the preamorphized Si substrate than in BF2+ -implanted samples. Rapid thermal annealing was performed to obtain kinetic data for the formation of polycrystalline Si grains. The nucleation and growth of polycrystalline Si grains were found to occur in the amorphous phase ahead of the growing a-c interface. The incubation time for the formation of 4nm or larger crystallites in amorphous Si at 700oC was found to be less than 30s. The results are discussed in terms of the competition between the propagation of the a-c interface to sweep over the potential nucleation sites and random nucleation in the amorphous phase. Ramifications of the formation of polycrystalline Si grains in instances with a relatively low ion dosage and/or moderate annealing temperature are addressed.[[fileno]]2020412010013[[department]]工工