Surfactant enhanced growth of thin Si films on CaF 2/Si(1 1 1)

Abstract

MBE growth of Si thin films on CaF 2/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 CaF 2 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 CaF 2, with a sharp ( 3 x 3 )R30° 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.