Kinetic Monte Carlo simulation of MBE growth of layered hexagonal Boron Nitride
Hexagonal boron nitride (hBN) is a two-dimensional atomically thin semiconductor material. It is expected to exhibit fascinating electronic, photonic, and thermal properties. To obtain atomically thin monolayers, chemical vapor deposition (CVD) and molecular beam epitaxy (MBE) has been employed to grow hBN on different substrates. However, the high density of grain boundaries and other defects limit the potential of hBN. A deep understanding of the physics of crystal growth, facilitated by the substrate surface in an MBE environment is necessary to improve the synthesis technique for high-quality hBN. In this work, we have analyzed the hBN deposition and diffusion process using Nudged Elastic Band, and the transition state theory. A Kinetic Monte Carlo (KMC) model is constructed to simulate hBN MBE growth under various temperatures, flux ratios, and flux rates. The model is calibrated with experimental data and has produced reliable predictions of hBN growth dynamics, propensities to form various geometric configurations, growth rates, and nucleation properties. In addition, the model captures the influence of input N isotope (N14 and N15) ratios and the number of layers on hBN Raman spectra. A Raman peak shift, from 1359 cm-1 (100% N14) to 1339 cm-1 (100% N15), has been observed. It is found that increasing the deposition thickness will lead to transitions of hBN Raman peaks. The KMC model developed here and the findings of this study for hBN should prove useful to a wider class of 2D materials.
Hexagonal Boron Nitride; Molecular Beam Epitaxy; Materials Science; Kinetic Monte Carlo
Xing, Huili Grace
Materials Science and Engineering
M.S., Materials Science and Engineering
Master of Science
dissertation or thesis