Low-temperature relaxation of elastic stresses in SiGe/Si heterostructures irradiated with Ge+ ions

Abstract

Pseudomorphic Si0.76Ge0.24/Si heterostructures grown by molecular-beam epitaxy were irradiated with 350-keV Ge+ ions at a temperature of 400°C so that the peak of the ions’ energy losses was located within the silicon substrate (deeper than the SiGe-Si interface). The effect of ion implantation on the relaxation of elastic stresses and the defect structure formed as a result of postimplantation annealing is studied. It is found that annealing at a temperature even as low as 600°C makes it possible to ensure a very high degree of relaxation of elastic stresses in the heterostructure and a comparatively low density of threading dislocations in the SiGe layer (<105 cm−2). The results obtained make it possible to suggest a method for the formation of thin SiGe/Si layers that feature a high degree of relaxation, low density of threading dislocations, and a good surface morphology.