分子动力学方法模拟GaN薄膜生长

Molecular dynamics simulations on GaN film growth

采用分子动力学模拟方法,应用Bucking-ham经验势模型,模拟纤锌矿相GaN的薄膜晶格生长。研究了GaN薄膜生长的早期阶段的形貌特点、生长规律、表面结构及动力学特性。模拟发现,N原子与Ga原子按照晶格特征吸附在衬底上,作层状分布趋势并且薄膜层从下到上晶态特征逐渐减弱。观察每层沉积原子数、空位比、沉积原子团簇质心高度与沉积原子均方位移随时间的变化规律,发现了随着时间步数增加,原子团簇逐渐达到稳定,在5000步时前3层都达到了较稳定状态,且N原子比Ga原子能更快地找到平衡位置。

Molecular dynamics simulations using a Buckingham potential have been used to investigate the process of wurtzite GaN films growth, including the appearance of films in early stage, regulation of growth, structure of the surface and the dynamics features. The simulations showed that N atoms and Ga atoms were absorbed on the lattice of substrate and took on a distinct samdwich structure the crystalline character of the films became weaker from bottom to top. Time evolution of the number of the atoms deposited on every layer, the vacancy ratio of every layer, the height of the centre of mass of the deposited clusters and the mean square displacements of the atoms were observed, the results showed that the clusters became stable with the time steps increasing and the first three layers had reached the stable state in the first 5000 steps, besides, N atoms reached the equilibrium positions more quickly than Ga atoms.