Silicide mediated low temperature crystallization of hydrogenated amorphous silicon in contact with aluminum

The reaction between hydrogenated amorphous silicon (a-Si:H) film and aluminum has been investigated by Transmission Electron Microscopy and Scanning Electron Microscopy (SEM). The formation of aluminum silicide was observed even at room temperature. Subsequent annealing of the sample showed [111], [110] and [311] orientations of aluminum silicide coexisting as revealed by the electron diffraction patterns. This silicide has a bcc structure with lattice parameter of 6.36 Å. The precipitation of Si at the interface was observed in SEM after selective etching of Al from the top surface of the sample. The silicide disappears completely at 300 °C with the formation of polycrystalline and porous silicon. The effect of temperature related structural changes on the electrical properties of Al/a-Si:H Schottky diode has also been studied.