X-ray pole figure analysis on columnar-structured microcrystalline silicon: Growth-induced crystallographic axial alignment in solid phase

Abstract

Angular distributions of crystallographic axes of the microcrystalline silicon (μc-Si) thin films have been investigated using the x-ray pole figure measurements with an emphasis on the growth-induced changes in the first growth regions of the μc-Si films. The (220) preferentially oriented μc-Si films containing columnar microstructures were prepared by plasma enhanced chemical vapor deposition with differing thicknesses. The distributions in the tilt angles of ⟨220⟩ axes from the substrate normal decreased with increasing the film thickness, particularly in the first 0.5μm growth regions. Meanwhile, such a change was not found in ⟨111⟩ axes. Moreover, the x-ray pole figure measurements were also carried out for the (111) preferentially oriented μc-Si films containing granular microstructures, revealing that no pronounced change in the tilt angles of ⟨111⟩ axes were found during the film growth. Therefore, the axial alignment should be specific to the ⟨220⟩ axes in the μc-Si films with the (220) preferential orientation. In conjunction with the other experimental results on the microstructures, the growth-induced structural changes in solid phase are discussed.