Formation process of interface states at grain boundaries in sputtered polycrystalline Si films

A systematic investigation has been made on surface defect states of crysta llites in the crystallization process of sputtered amorphous silicon films by isothermal annealing. Transmission electron microscopic observations ind icate a pronounced vertical columnar structure in the upper part of the fil ms, where the crystallization is delayed. Admittance spectroscopy reveals t hat two newly generated energy levels with the crystallization are attribut ed to the crystallites in the lower and upper parts of the films in view of the anisotropic crystallization. These thermally induced changes can be we ll explained by Si-Si shearing modes at the interfaces of crystallites thro ugh the process of crystallization.