Grain-boundary defects in laser-crystallized polycrystalline silicon

Abstract

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 ${T}_{S}=300$ and 673 K poly-Si films with grain sizes of 1.5 and 1.0 \ensuremath{\mu}m were obtained at laser fluences of 540 and $505{\mathrm{m}\mathrm{J}/\mathrm{c}\mathrm{m}}^{2},$ 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 \ifmmode^\circ\else\textdegree\fi{}C. This causes the spin density to decrease to a residual value of $\ensuremath{\approx}9\ifmmode\times\else\texttimes\fi{}{10}^{16}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ independent of substrate temperature and laser fluence.