Large area polycrystalline silicon thin films grown by laser-induced nucleation and solid phase crystallization

We present investigations on a two-step technique for the growth of polycrystalline silicon thin films on glass substrates. In the first step, a lattice of artificial seeds is created by laser crystallization of amorphous silicon. In the second step, crystallites are grown around the seed by thermal annealing below 600 °C. For seed separations of 7 μm, adjacent crystallites can coalesce before spontaneous nucleation becomes apparent. Transmission electron microscopy reveals that the crystallites are star shaped, consisting of domains separated by twin boundaries. Microscopic reflection difference spectroscopy measurements reveal the existence of a radial stress pattern around the seeds. We conjecture that this stress drives the lateral growth around the seeds during thermal annealing.