Influence of laser crystallization on hydrogen bonding in poly-Si

We investiage the influence of the hydrogen content in the amorphous starting material on hydrogen bonding and defect passivation in laser crystallized poly Si using electron spin resonance and hydrogen effusion measurements. After laser dehydrogenation and crystallization the specimens contain a residual II concentration of 8x10(21) cm to 1.5x10(22) cm(-3). During a vaccum anneal at least 1.5x10(21) cm H atoms are mobile in the lattice, however only about 3.7x10(18) cm H atoms passivate Si dangling bonds. Our results show that the anneal treatment can cause the vast majority of H atoms to accumulate in H stabilized platelets. Since defect passivation preferentially occurs at grain boundaries and platelet nucleation and growth is confined to the interior of single crystal grains. H equilibration is governed by two patially separated process. Moreover, our data demonstrate that the hydrogen density of states distribution derived form H effusion data is dynamic and changes in response to experimental parameters. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.