Grain-boundary defects in laser-crystallized polycrystalline silicon

Polycrystalline silicon (poly-Si) films were prepared by laser crystallization of amorphous silicon with various laser energy densities at substrate temperatures of 300 and 673 K. At TS=300 and 673 K poly-Si films with grain sizes of 1.5 and 1.0 {μ}m were obtained at laser fluences of 540 and 505mJ/cm², respectively. An increase of the grain size results in a decrease of the spin density due to a reduction of the grain-boundary volume. Moreover, the increase in substrate temperature resulted in a pronounced decrease of the spin density independent of the laser energy density. Defects are passivated by exposing the poly-Si films to monatomic H at 350 ^∘{}C. This causes the spin density to decrease to a residual value of ≈9×10¹⁶cm^-3 independent of substrate temperature and laser fluence.