Low temperature growth of Si:Ce thin films with high crystallinity and uniform distribution of Ce grown by solid-source molecular beam epitaxy

Diluted magnetic semiconductor (DMS), Si:Ce thin films with the Ce concentration below 0.3 at%, are prepared on (0 0 1) Si substrates by low-temperature molecular beam epitaxy (LT-MBE) method. Since a smooth surface is obtained by optimizing the surface-cleaning processes of Si substrate and the deposition conditions of buffer layer, Si:Ce thin films are able to be grown at the growth temperature of 450 degrees C. RHEED oscillations are observed at the initial stage of the growth, indicating two-dimensional growth. The LT growth enables to obtaining uniform distribution of Ce in Si without hillock or pit formation. The X-ray diffraction (XRD) patterns reveal that all the films are. grown epitaxially on the (001) Si substrate and no extra diffractions corresponding to the silicide are recognized. (C) 2007 Elsevier B.V. All rights reserved.