Surfactant enhanced growth of thin Si films on CaF2/Si(111)

MBE growth of Si thin films on CaF2/Si(1 1 1) has been studied by various growth techniques with and without surfactant. In both cases high temperature depositions results in a growth of 3D Si clusters and a large discrepancy between the nominally evaporated and the actually deposited amount of Si on the CaF2 surface. Without surfactant, the deposition at room temperature with a subsequent annealing steps improved the quality of the Si epilayers but was accompanied by the formation of holes and trenches in the Si film. A surfactant-modified epitaxy method, where the room temperature Si deposition was followed by annealing under a flux of the surfactant Sb, resulted in continuous, smooth and epitaxial crystalline Si film on CaF2, with a sharp (root3 x root3)R30degrees reconstruction. Although the microcrystalline structure is not yet perfect the quality of the layers is much better than that of all films prepared by the other employed growth processes. (C) 2003 Elsevier Science B.V. All rights reserved.