Morphological, structural and luminescence properties of Si/β-FeSi2/Si heterostructures fabricated by Fe ion implantation and Si MBE

The morphology and optical properties of Si samples implanted by low- energy Fe+ ions with different fluences ( 1 x 10(15) - 1.8 x 10(17) cm(- 2)) and further subjected to pulsed ion- beam treatment ( PIBT) have been studied by atomic force microscopy and optical reflectance spectroscopy. It was proved that iron disilicide (beta- FeSi2) crystallites were formed on the surface of the Si substrate as a result of ion implantation and PIBT. The method of ultrahigh vacuum and low- temperature ( T = 850 degrees C) cleaning of Fe+- implanted Si samples has been applied for the first time. It was found that it is possible to form smooth epitaxial Si films with both a thickness of up to 1.7 mu m and a reconstructed surface by molecular beam epitaxy on the surface of Si samples implanted with a fluence of up to 1 x 10(16) cm(- 2). Further increase in the implantation fluence results in the disruption of epitaxial Si growth and to a strong increase in surface relief roughness due to 3D silicon growth mechanism. Preservation of beta- FeSi2 precipitates inside the Si matrix after the formation of a cap epitaxial Si layer has been confirmed by optical spectroscopy data. Low temperature photoluminescence measurements in the range 1400 - 1700 nm showed that light emission of the formed Si/ beta- FeSi2/ Si heterostructures is due to contributions from beta-FeSi2 precipitates and dislocations.