Reactive Force-Field Molecular Dynamics Study of the Effect of Gaseous Species on SiliconGermanium Alloy Growth by PECVD Techniques

Reactive Force Field Molecular Dynamics Studies of the Initial Growth of Boron Nitride Using BCl3 and NH3 by Atomic Layer Deposition

“…The first bottom layer of the substrate was fixed, and the second and third layers were controlled at 750, 1000, 1250, 1500, 1750, and 2000 K. To minimize the unexpected influence of velocity changes of substrate atoms on surface events, temperatures were indirectly maintained so that only the velocity of atoms in the fourth and subsequent layers were controlled to be a desired temperature, and the velocity atoms in the second and third layers were not controlled but they exchange energy between the controlled third and fourth layers. This temperature control scheme has been employed in the related film growth simulations. ,, After the OH-Si(100) substrate was relaxed with the NVT ensemble for 100 ps, ALD cycles were performed by repeating (1) BCl 3 pulse, (2) first purge, (3) NH 3 pulse, and (4) second purge as shown in Figure . For the pulse processes, BCl 3 or NH 3 molecules were added one by one to the system with an incident velocity of 300 K, meaning only the z- direction component with the associated incident energy to simplify the zero-incident-angle system.…”

“…Although significant studies based on DFT simulations at 0 K without consideration of the temperature effect have been reported, studies that describe the dynamics of the formation and breaking of bonds at certain temperature conditions are still missing. As a relatively new approach, ReaxFF reactive force field-based molecular dynamics (ReaxFF MD) simulation is a powerful technique for understanding the growth mechanism, including both the physical dynamics like diffusion and chemical reactions simultaneously. − As parameters are trained against quantum mechanics (QM) data, ReaxFF MD simulations can approach the accuracy of DFT calculations with a larger system size and much lower computational cost compared with those of DFT calculations.…”

Reactive Force Field Molecular Dynamics Study of the Effects of Gaseous Species on the Composition and Crystallinity of Silicon–Germanium Thin Films

“…Another approach is to perform all-atom MD simulations using an empirical interatomic potential. ,− The increasing power and popularity of MD simulation arise because the quality of interatomic potentials has become quite suitable for some systems, and computer speeds continue to increase year by year. A relatively new and promising trend in developing simulation methods is the so-called reactive force fields molecular dynamics (ReaxFF MD) by van Duin and coworkers. − This method has been applied to a wide range of materials, including amorphous and crystalline SiO 2 and Al 2 O 3 , yielding excellent agreement with experimental structural parameters, mechanical properties, and infrared spectra of bulk silica. − The ReaxFF MD enables us to understand the growth mechanism by repeatedly adding gaseous species, including physical dynamics and chemical reactions. − ReaxFF MD, which is not a lattice-based simulation, can also evaluate the film crystallinity with atomic relaxations that are not accessible using basic KMC methods. The limited accessible simulation time and length represent substantial obstacles in making valuable predictions with this ReaxFF MD approach.…”