Perfect, partial, and split dislocations in quantum dots

Abstract

A mechanism for relaxation of misfit stresses in nanoislands (quantum dots) is theoretically examined which is the formation of partial and split misfit dislocations. The parameters of nanoislands with perfect, partial, and split misfit dislocations are estimated and compared, with emphasis on the case of Ge/Si nanoislands. Different dislocation structures are shown to be energetically preferred in different regions of the nanoisland/substrate interface. It is theoretically revealed that perfect misfit dislocations (conventionally considered in models of dislocated nanoislands) are not energetically favorable in pyramidlike nanoislands in Ge/Si system. Also, it is shown that misfit dislocation formation is capable of causing nanoisland shape transformation as an energetically favorable process.