Quantitative modelling of nucleation kinetics in experiments for poly-Si growth on SiO2 by hot wire chemical vapor deposition
Abstract We apply a rate-equation pair binding model of nucleation kinetics to the nucleation of Si islands grown by hot wire chemical vapor deposition on SiO 2 substrates. The grain size of poly-Si films increases with H 2 dilution, which is attributed to atomic H etching of Si monomers rather than stable Si clusters during the early stages of nucleation. The nucleation density increases sublinearly with time at low coverage, implying a fast nucleation rate until a critical density is reached, after which grain growth begins. The nucleation density decreases with increasing H 2 dilution (H 2 :SiH 4 ) due to etching, and with increasing temperature, due to enhanced Si monomer diffusivity on SiO 2 . From temperature-dependent measurements, we estimate the activation energy for surface diffusion of Si monomers on SiO 2 to be 0.47±0.09 eV. Simulations of the temperature-dependent supercritical cluster density lead to an estimated activation energy of 0.42±0.01 eV and an estimated surface diffusion coefficient prefactor of 0.1±0.03 cm 2 /s.
Selective silicon nanoparticle growth on high-density arrays of silicon nitride
Abstract Selective silicon nanoparticle deposition from disilane on ∼17 nm diameter Si 3 N 4 features defined through a 15-nm-thick SiO 2 masking layer was studied using hot wire chemical vapor deposition between 900 and 1025 K, and chemical vapor deposition between 900 and 975 K. Thin film poly(styrene-b-methyl methacrylate) diblock copolymer was used to generate cylinders with a density of 6×10 10  cm −2 that served as the patterning template. Silicon adatom etching of SiO 2 and diffusion of adatoms to the Si 3 N 4 regions prevented the accumulation of adatoms necessary for nanoparticle nucleation and growth on the SiO 2 surfaces. Nanoparticles form selectively on Si 3 N 4 , because adsorbed Si does not etch this surface. Incident flux, total exposure, and substrate temperature were adjusted to explore nanoparticle deposition trends relating relative adatom concentration with nanoparticle density and size distributions.
Phenomenology and Existentialism
Chapter 1 Preface to the 2001 Edition Chapter 2 Introduction Part 3 The Phenomenology of Edmund Husserl Chapter 4 The Attack on Psychologism Chapter 5 The Phenomenological Reductions Chapter 6 Phenomena and Phenomenological Reflection Chapter 7 Intentionality Chapter 8 Meaning and Constitution Chapter 9 Essences and Necessary Truth Part 10 Existential Phenomenology Chapter 11 Phenomenology and Ontology Chapter 12 Existence Chapter 13 The Life World Part 14 Self and Others Chapter 15 Consciousness and the Ego Chapter 16 Intersubjectivity Chapter 17 Freedom Chapter 18 Existentialist Ethics Chapter 19 Bibliography