The effect of oxygen on the thermal stability of Si1−xGex strained layers

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Abstract
The thermal stability of Si1−xGex strained layers containing 2×1020 oxygen atoms/cm3 is compared with that of similar layers (same Ge fraction and film thickness) containing more than two orders of magnitude less oxygen. For the layers with high oxygen levels, no misfit dislocations were found in films as thick as two times the theoretical equilibrium critical thickness, after annealing at 850 °C for 4 min. In contrast, dislocations were found in the layers with low oxygen levels at thicknesses very near the equilibrium critical thickness after the same anneal. X‐ray measurements of lattice constants in high and low oxygen films of similar Ge content indicate that oxygen does not substantially change the amount of strain in the layers. Oxygen appears to impede the kinetics of dislocation formation.