Thermal stability of Si/GexSi1−x/Si heterostructures

Abstract

The thermal stability of Si/Ge_xSi_1−x/Si (100) heterostructures is studied by in situ electron microscope observations of the thermal relaxation process. Structures are observed to relax by misfit dislocation propagation at both strained interfaces, and are stable to significantly higher temperatures than equivalent strained Ge_xSi_1−x layers at a free surface. This observed difference in thermal stability between double and single interface structures is due at least in part to much lower dislocation velocities in the double interface structures, with a measured glide activation energy approximately twice as high as single interface structures. It is argued that this difference in glide activation energies may be due to a smaller kink nucleation activation energy in the single interface structure.