Modified dislocation structures in Ge(x)Si(1-x) double epilayers on (001) Si.

摘要

Double epilayers of different compositions of Ge(sub x)Si(sub 1(minus)x) on (001) Si are observed to have dislocation contents which differ markedly from similar single epilayers. An initial epilayer, grown below its critical thickness, underwent substantial misfit dislocation introduction, while a second epilayer, grown at a composition where edge-type misfit dislocations are normally observed to dominate the morphology, contained mostly 60(degree) type dislocations. It is suggested that dislocation entry into the upper, high mismatch epilayer allows many dislocations to enter the buried, low mismatch epilayer, and that this in turn affects the dislocation morphology in the upper layer through strain relief. 7 refs., 3 figs.