The effect of composition on the thermal stability of Si1-x-yGexCy/Si heterostructures

The thermal stability of molecular beam epitaxy grown Si1-x-yGexCy/Si heterostructures (0 less than or equal to x <0.30, y similar to 0.008) was studied using infrared absorption spectroscopy, The local vibrational mode of C in Si and Si1-x-yGex was used to quantify the loss of C atoms from substitutional sites with high temperature annealing. The activation energy (E-a=4.9 eV) for the loss of substitutional C achieved a maximum for the strain compensated alloy (x similar to 0.1). An additional increase of Ge content resulted in a rapid decrease in E-1, which was found to be 3.4 eV for x similar to 0.27. The nonmonotonic behavior of E-a on Ge content is explained by the effect of the inter-fact strain between the epitaxial layer and Si substrate. (C) 1998 American Institute of Physics.