Effect of surface segregation on the sharpness of heteroboundaries in multilayered Si(Ge)/Si1-xGex structures grown from atomic beams in vacuum

The main reasons for composition intermixing in the vicinity of heterobound aries in an Si(Ge)/Si1-xGex heterosystem grown by the molecular beam epitax y method are considered. The proposed model explains all the experimentally observed peculiarities, such as the clearly manifested asymmetry of the so lid solution profile in layers, and demonstrates the noticeable erosion of the composition profile at the boundaries even in the absence of the surfac e segregation effect. It is shown that the surface segregation in the Ge/Si 1-xGex system may play a positive role, leading to an increase in the profi le steepness of the Si1-xGex layer near the boundaries. (C) 2001 MAIK "Nauk a/Interperiodica".