Effect of grain alignment on lateral carrier transport in aligned-crystalline silicon films on polycrystalline substrates

We report the studies on the effect of grain alignment on lateral carrier transport in nominally 〈001〉-oriented aligned-crystalline silicon (ACSi) films on polycrystalline substrates. With improving grain alignment, energy barrier height at the grain boundaries was reduced from 150 to less than 1 meV, and both conductivity and Hall mobility became less sensitive to hydrogen passivation. This suggests that the dangling bonds in ACSi films are a major source of trapping sites, and that they become less dominant with improving grain alignment. These results demonstrate that improving grain alignment enhances the lateral carrier transport in small-grained (≤1 μm) polycrystalline silicon films, by reducing dangling bond density at the grain boundaries.