| Understanding the atomic-scale mechanisms of solid-state diffusion in semiconductor materials at elevated temperatures is of broad scientific and technological interest. Experimental study of diffusion mechanisms is key to unveiling the properties of the native point defects in semiconductors, providing quantitative comparison to theoretical results from first-principles calculations. These properties, moreover, serve as key parameters for improving the performance of integrated circuits.; In this thesis, we have studied self-diffusion in silicon, the most fundamental diffusion process in the most widely used semiconductor material. Diffusion of atoms in silicon can occur either by a direct mechanism or via intermediate species. These intermediate species are formed by the interaction of substitutional atoms with the native point defects in the lattice, namely self-interstitials and vacancies. Although previous work has shown that phosphorus and boron predominantly diffuse by an interstitial mechanism and that antimony diffuses by vacancies, a long-standing controversy has existed over the dominant diffusion mechanisms for arsenic and self-diffusion in silicon.; We have resolved this controversy by measuring self-diffusion directly using epitaxially-grown isotopically enriched silicon structures, which have become available only recently. By studying the diffusion of four dopants and self-diffusion under point defect perturbation in the range 800–1100°C, we have shown that arsenic and self-diffusion in silicon take place by a dual vacancy-interstitial mechanism at elevated temperatures. Furthermore, we have extracted the activation enthalpies and entropies for the interstitial and vacancy mechanisms of self-diffusion for the first time. We have also studied self-diffusion under extrinsic carrier conditions, yielding some of the properties of charged point defects in silicon.; We have then applied these basic results in areas such as metal diffusion, high concentration dopant diffusion, and ultra shallow junction formation. |
