Kinetic Monte Carlo model for homoepitaxial growth of Ga_{2}O_{3}

Abstract

We developed a kinetic Monte Carlo (KMC) model for the homoepitaxy of β-Ga_{2}O_{3}. It comprises adsorption, diffusion, and desorption and reflects the structure of β-Ga_{2}O_{3} with its two kinds of atoms: Ga and O. The knowledge gained from metal organic vapour phase experiments (MOVPE) experiments combined with AFM and TEM characterisation was used for the setup of rules and activation energies for the various surface processes. We performed a set of runs for the growth on flat and vicinal (100) surfaces. The nucleation on the flat surface requires a minimum ratio of the impingement rate of O_{2} and Ga. The behavior at different substrate temperatures was similar in experiment and in simulation. At high temperatures, we observe the formation of large islands whereas at low temperatures small islands are formed. The growth rate is increasing with decreasing temperature. On a vicinal surface (6^{∘}) different growth modes have been observed when using different desorption energies. Low desorption energy (high desorption rate) leads to step bunching, intermediate to step growth, and high energy (low desorption rate) to nucleation on terraces with a final configuration similar to step bunching.