Heteroepitaxial growth of Ge films on Si substrates by molecular beam epitaxy

A new approach of growing thick Ge layers on Si substrates by molecular beam epitaxy is presented. A 30–80 Å thick Ge overlayer is first deposited on the Si(100) substrate at room temperature. By thermally annealing the sample to 300 or 500 °C for 10 min, the Ge atoms cluster into randomly distributed islands which would play a role in releasing the mismatch stress at the interface. The Ge film of 10 000 Å thickness epitaxially grown on this surface at 550 °C shows a better crystalline quality than that grown by a conventional method. A full width at half maximum of 262 s for the Ge (400) x-ray diffraction peak has been achieved.