Structure and grain boundary defects of recrystallized silicon films prepared from amorphus silicon deposited using disilane

Abstract

The structure of polycrystalline Si (poly-Si) films, prepared by annealing amorphous Si (a-Si) films deposited using Si2H6, has been investigated by x-ray diffraction (XRD), Raman scattering, transmission electron microscopy (TEM), and electron spin resonance, as functions of deposition conditions, such as deposition temperature Td (450–580 °C) of the a-Si and annealing time under a fixed temperature of 600 °C. A dominant texture of the poly-Si films changed from a 〈100〉 texture for Td below 530 °C to a 〈111〉 for Td above 530 °C, independent of the deposition rate of the a-Si films and of the film thickness. Although the XRD grain size was independent of Td, the TEM grain size increased from 1.0 to 2.5 μm with decreasing Td. It is suggested that the increase in this TEM size is caused by enhanced lateral growth of 〈100〉 grains due to the presence of strain. The spin density Ns and the factor g were found to first increase with the annealing time, and rapidly decreased after the films were crystallized. It is also found that the value of g for the poly-Si films decreased from 2.0051 to 2.0048 with decreasing Td. Furthermore, effects of post-hydrogenation on the poly-Si films with different textures were investigated, and a structural change of the boundary regions in the poly-Si films is discussed in connection with a change in the dominant texture, through the corresponding change in g.