Effect of oxide layer on Al-induced crystallization of amorphous Si1−xGex thin films

Metal-induced crystallization (MIC) of amorphous silicon-germanium (a-Si_1-xGe_x) thin films at lower temperature is of considerable importance in photoelectric applications, such as, photovoltaic solar cells, thin film transistors (TFT), larger screen liquid crystal display (LCD), and so on. In this paper, bi-layer Al/a-Si_1-xGe_x thin films on glass substrates were prepared by sputtering deposition, and aluminum oxide layers were involved in some samples. After annealed at 350°C for a long time, the surface morphology, the crystallization degree, the compositional distribution as well as grain sizes of the crystallized SiGe thin films were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and Auger electron spectroscopy. According to the results, the effect of oxide layers on the Al-induced crystallization of a-Si_1-xGe_x thin films and the accompanying layer exchange were discussed. It was shown that the additional aluminum oxide layers may significantly improve the crystallization of amorphous thin films; a relevant mechanism was suggested to illuminate this phenomenon.