Effect of substrate modulus difference on dislocation formation in an epitaxial film

The effect of substrate modulus difference on dislocation formation in an e pitaxial film is derived in the present study. The analysis is based on the energy approach, in which the self-energy of the dislocation and the inter action energy between the dislocation and the mismatch strain are calculate d. The elastic stress field due to the interface dislocation is derived by superposition of the elastic stress fields of the film/substrate system wit h the following two configurations: (i) a dislocation at the interface assu ming the film is also semi-infinite, and (ii) prescribed traction on the fi lm surface which are the negative of those calculated from the first config uration at the location equivalent to the film surface in the second config uration. The results show that the critical film thickness for forming inte rface dislocation increases with the decrease in the shear modulus ratio of the film to the substrate. (C) 2001 Elsevier Science Ltd. All rights reser ved.