Papers by Keyword: Rate Equation

Abstract: Computer simulation of the concentration profiles evolution in SiC/Si heterostructures during growth and subsequent ion sputtering is presented. Simulation is based on a complex self-consistent approach combining kinetic and ballistic methods. Within the framework of the proposed method concentration depth profiles in SiC/Si heterostructure with pre-deposited Ge impurity are calculated and compared with experimental sputtering profiles obtained by secondary ion mass spectrometry.

Abstract: A new rate equation developed by Yamamoto was applied to the rate of recovery and recrystallization in pure aluminum. The entire reaction can be expressed by Yamamoto’s equation because it contains the term of particle number. By applying this equation, the entire reaction process was divided into two reactions, the recovery and recrystallization. The obtained values of the time-exponent are 0.5 in the former and 1 in the latter regardless of the soaking conditions and annealing temperatures. Based on the microstructures and time-exponents, it is concluded that the rate of recovery and recrystallization is controlled by the precipitation of silicon on the dislocation cell boundaries during the recovery process and the precipitation of iron on the subgrain boundaries during the recrystallization one.

Abstract: Long-External Cavity Laser (L-ECL) is a kind of new and promising type laser because of its dynamic single mode performance. In this paper, firstly, the theory model of L-ECL is discussed; Secondly, the influence of coupling coefficient on the threshold gain of L-ECL is studied based on equivalent external cavity theory; Thirdly, utilizing the theory of equivalent cavity length, combined rate equations, the high frequency response characteristic of L-ECL is analyzed; Lastly, optical spectrums of L-ECL on different grating peak reflectivity are obtained by experiment.

Abstract: We investigate the effect of carrier dynamics on the temperature dependence of photoluminescence spectra from InAs/GaAs quantum dot heterostructures with different dot size uniformity. Intersublevel relaxation lifetimes and carrier transferring mechanisms are simulated using a model based on carriers relaxing and thermal emission of each discrete energy level in the quantum dot system. Calculated relaxation lifetimes are decreasing with temperature and have larger values for sample with lower dot size uniformity. In the quantitative discussion of carrier dynamics, the influence of thermal redistribution on carriers relaxing process of quantum dot system is demonstrated by our model.

Abstract: Diffusion phenomena in solid particles were analyzed with the new material transport concept. It was assumed that total excess free energy in a system acted as a driving force for material transport so that the system changed to an equilibrium state. The new rate equation was adopted to analyze shape change, sintering and growth of grains. It was found that surface energy or ratio of grain boundary energy to surface energy was key factor for shape changes in these processes.

Abstract: Physical vapor deposition technique has been employed to develop a thin film of OLED, and atomic force microscopy was used to investigate the boundary characteristics such as uniformity of emitting layer, roughness, and surface morphology. In order to determine the deposition characteristic which associated with the materials failure in OLED, finite element simulation, together with alternative analytical modeling has been carried out by means of island growth mechanism analysis. The boundary growth of thin film can be determined from the velocity of island boundary using simple rate equations. The results obtained are compared with experimental observation. Generally good agreement has been achieved.

Abstract: Solid source molecular beam epitaxy was applied to create silicon carbide nanoclusters on silicon. The island size distribution can be controlled by an appropriate substrate temperature, carbon fluxes and process times. Rate equation computer simulation was applied to simulate the experimental obtained nano scale nuclei properties.

Abstract: This article introduces a 3D cellular automaton model for the prediction of spherulite growth phenomena in polymers at the mesoscopic scale. The automaton is discrete in time, real space, and orientation space. The kinetics is formulated according to the Hoffman-Lauritzen secondary surface nucleation and growth theory for spherulite expansion. It is used to calculate the switching probability of each grid point as a function of its previous state and the state of the neighboring grid points. The actual switching decision is made by evaluating the local switching probability using a Monte Carlo step. The growth rule is scaled by the ratio of the local and the maximum interface energies, the local and maximum occurring Gibbs enthalpy of transformation, the local and maximum occurring temperature, and by the spacing of the grid points. The use of experimental input data provides a real time and space scale.