Overlayer stress effects on defect formation in Si and Ge

• Published in: Thin solid films 2010-02, Vol.518 (9), p.2442-2447
• Main Authors: Cowern, Nick E.B., Bennett, Nick S., Ahn, Chihak, Yoon, Joo Chul, Hamm, Silke, Lerch, Wilfried, Kheyrandish, Hamid, Cristiano, Filadelfo, Pakfar, Ardechir
• Format: Article
• Language: English
• Subjects: Activation; Condensed Matter; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Diffusion; Diffusion; interface formation; Engineering Sciences; Exact sciences and technology; Germanium; Materials; Materials Science; Micro and nanotechnologies; Microelectronics; Nitride; Physics; Point defects; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Silicon; Solid surfaces and solid-solid interfaces; Strained overlayers; Stress; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2009.09.142

Point-defect formation energies in bulk crystalline materials such as Si and Ge are material specific quantities defined for the case of formation at a free surface, but in many cases of technological interest, point defects are 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 is 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 impacts on diffusion, defect formation and activation of dopant impurities in the substrate. We present current experimental evidence for this phenomenon, based on studies of B diffusion under tensile-strained nitride layers, and discuss the likely implications for dopant activation in Si and Ge.