A Model for Thermal Growth of Ultrathin Silicon Dioxide in O2 Ambient: A Rate Equation Approach

A new thermal oxidation model based on a rate equation approach with concentration dependent diffusion coefficient is proposed for ultrathin SiO2 for thicknesses of the order of 100 Å. The oxidation reaction of silicon is assumed to be dependent on the concentrations of unreacted silicon and oxygen. The results of oxide thickness versus oxidation time for various growth conditions and activation energies for diffusion coefficients are in agreement with various experimental data for O2 ambient

A Stochastic Model for Crystal-amorphous Transition in Low Temperature Molecular Beam Epitaxial Si(111)

Molecular beam epitaxial Si (111) grown below a certain temperature result in amorphous structure due to the limited surface mobility of atoms in finding correct epitaxial sites. In spite of many experimental and theoretical studies, the mechanism of crystal‐amorphous transition and its dynamics related to the growth conditions are not well understood. In this article, we present a theoretical model based on the formation of stacking fault like defects as a precursor to the amorphous transition of the layer. The model is simulated based on a stochastic model approach and the results are compared to that of experiments for temperatures in the range of 500–900 K and growth rate in the range of 0.1–3.0 Å/s. The agreement between our results and experimental observations is excellent

Theoretical Study of Antisite Arsenic Incorporation in the Low Temperature Molecular Beam Epitaxy of Gallium Arsenide

A stochastic model for simulating the surface growth processes in the low temperature molecular beam epitaxy of gallium arsenide is developed, including the presence and dynamics of a weakly bound physisorbed state for arsenic. The physisorbed arsenic is allowed to incorporate into the arsenic site or gallium site (antisite) and evaporate. Additionally, the antisite As is allowed to evaporate from the surface of the crystal. The arsenic flux, temperature and growth rate dependences of antisite arsenic (AsGa) concentration and the resultant % lattice mismatch obtained from our simulation are in excellent agreement with the experimental results. The activation energy of 1.16 eV for the evaporation of antisite arsenic from the crystal obtained from our model is in good agreement with theoretical estimates. At a constant substrate temperature and growth rate (Ga flux rate), the antisite arsenic concentration and hence, the % lattice mismatch increase with arsenic flux in the low flux regime and saturate for high flux regime. The critical arsenic flux at which the AsGa concentration and the % lattice mismatch saturate, increases with temperature. The AsGa concentration and % lattice mismatch saturate at lower values for higher temperatures. As the arsenic flux increases, the coverage of the physisorbed layer increases and at a critical flux dictated by the fixed temperature and growth rate, the coverage saturates at its maximum value of unity (a complete monolayer) and hence, the concentration of AsGa and % lattice mismatch saturate. Lower AsGa concentration and % lattice mismatch result at higher temperature due to more evaporation of AsGa from the surface of the growing crystal. Additionally, an analytical model is developed to predict the AsGa concentration and % lattice mismatch for various growth conditions

A Stochastic Model for Crystal-amorphous Transition in Molecular Beam Epistaxial Si (111)

Molecular beam epitaxial Si (111) grown below a certain temperature result in amorphous structure due to the limited surface mobility of atoms in finding correct epitaxial sites. In spite of many experimental and theoretical studies, the mechanism of crystal‐amorphous transition and its dynamics related to the growth conditions are not well understood. In this article, we present a theoretical model based on the formation of stacking fault like defects as a precursor to the amorphous transition of the layer. The model is simulated based on a stochastic model approach and the results are compared to that of experiments for temperatures in the range of 500–900 K and growth rate in the range of 0.1–3.0 Å/s. The agreement between our results and experimental observations is excellent

Antisite Arsenic Incorporation in the Low Temperature MBE of Gallium Arsenide: Physics and Modeling

A stochastic model for simulating the surface growth processes in the low temperature molecular beam epitaxy of gallium arsenide is developed to investigate the incorporation of antisite As and its dependence on the growth conditions including the dynamics of the physisorbed As on the surface. Three different kinetic models with a combination of surface kinetic processes such as incorporation of antisite As, evaporation of antisite As and incorporation of regular As. The kinetic model with all three surface processes was accepted as the best model due to its physical soundness and reasonableness of its model parameters. The arsenic flux, temperature, and growth rate dependences of antisite arsenic (AsGa) obtained from our simulation are in excellent agreement with the experimental results. The activation energy of 1.16 eV and a frequency factor of 4×1012/s for the evaporation of antisite arsenic obtained from our model are in good agreement with experimental and theoretical estimates. At a constant substrate temperature and growth rate, the antisite arsenic concentration increases with arsenic flux for low fluxes and saturates beyond a critical flux. The critical arsenic flux increases with temperature and the saturation value of the AsGa concentration decreases with temperature. As the arsenic flux increases, the coverage of the physisorbed layer increases and at a critical flux dictated by the fixed temperature and growth rate, the coverage saturates at its maximum value of unity (a complete monolayer) and hence the concentration of AsGa saturates. Lower AsGa concentration results at higher temperature due to more evaporation of AsGa. Additionally, an analytical model is developed to predict the AsGa concentration for various growth conditions