Point-defect formation energies in bulk crystalline materials such as Si and Ge were material specific quantities defined for the case of formation at a free surface, but in many cases of technological interest, point defects were formed at the interface between the crystalline substrate and a strained material overlayer. Here the energy cost of generating a bulk point defect at the overlayer/substrate interface was modified by the stress interaction during defect formation, leading to an effective supersaturation or undersaturation in the bulk, relative to the ‘equilibrium’ concentration expected for the case of a free surface. This in turn affected diffusion, defect formation and the activation of dopant impurities in the substrate. Current experimental evidence for this phenomenon was presented; based upon studies of B diffusion under tensile-strained nitride layers, and the likely implications for dopant activation in Si and Ge were considered.

Overlayer Stress Effects on Defect Formation in Si and Ge. N.E.B.Cowern, N.S.Bennett, C.Ahn, J.C.Yoon, S.Hamm, W.Lerch, H.Kheyrandish, F.Cristiano, A.Pakfar: Thin Solid Films, 2010, 518[9], 2442-7