Ab Initio-based Monte Carlo Simulation Study for the Structural Stability of AlN Grown on 4H-SiC(11-20)

摘要

The Monte Carlo simulation is performed on the basis of our ab initio -based approach for adsorption-desorption behavior as a function of growth conditions.The distinctive atomic arrangements appear in subsequent adsorption of Al and N atoms after N and Al pre-depositions, respectively.After the N deposition, the subsequent Al adatom occupies the 4H lattice site similarly to the results for single Al on the surface.On the other hand, the N adatom tends to form the dimer structure with the pre-deposited Al.On the basis of these results, the electron counting Monte Carlo method is applied to investigate the atomic arrangements of AlN monolayer on the 4H-SiC(11-20) surface as a function of the III/V ratio.The simulated results imply that Al adatoms can easily occupy the 4H lattice sites to form the 4H-AlN layer at the III/V ratio greater than 10.In the range of the III/V ratio less than 0.1, the N adatoms reside in the stable interstitial sites to form the Al-N dimer layer or intermittently migrate to the 2H lattice site to form the 2H-AlN layer.This is qualitatively consistent with experimental results for the dependence of the structural stability on the III/V ratio.