In极性面InN的生长动力学行为

Abstract

采用第一性原理模拟计算方法,从原子层面出发,了解Inn的生长动力学行为.通过计算n和In原子于不同覆盖度下In极性表面的TOP、H3以及T4位置上的形成能和扩散势垒,了解沉积原子的相互作用和成核.结果表明,In原子比n原子更容易在干净的In极性表面吸附、粘接,并通过扩散找到稳定位置,形成一个较致密的双In原子层.模拟计算了n和In原子在双In原子层和三In原子层表面的扩散,结果显示,在稳定的双In原子层上,n原子将通过垂直扩散穿过顶部In原子层,并在两In原子层表面之间横向扩散,形成纤锌矿结构的Inn材料;然而,In原子虽然可形成三In原子层或In滴,其上沉积的n原子也仅能垂直扩散穿过顶部In原子层,长成新的Inn分子层,与Inn基底间存在双In原子层或更厚的In薄膜,形成不完整的纤锌矿结构Inn薄膜.在此基础上,我们提出一新的Inn外延两步生长法,以在生长过程中尽量保持表面只存在双In原子层结构,为高质量Inn薄膜的外延提供理论依据.

We try to understand the growth kinetic behavior of InN film at the the atomic level,using the first principles simulation method.By calculating the formation energies and barriers of N and In atoms at top,h3,and t4 site under different coverages,the interreaction and nucleation behaviors of the deposition atoms were known.The results showed that In atoms are more favourite to adsorb at a stable site on In polar surface by adhesion and diffusion,and form a compact In bilayer.Furthermore,the diffusion of N and In atoms were simulated on the In bilayer and trilayer.The results revealed that the N atoms will diffuse vertically into the top In layer of the stable In bilayer,and then form a wurtzite InN layer by lateral diffusion inside the In bilayer.Although an In trilayer or droplet can exist during the epitaxy,N atoms also can only penetrate into the top In layer,leading to a In bilayer or thick In film between deposited InN layer and the InN substrate,and an incomplete wurtzite InN film formed.On the basis of above results,we porpose a two-step growth method for InN epitaxy by keeping the In bilayer to achieve high quality InN film.