Timon V, Brand S, Clark S J, Abram R A
Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK.
J Phys Condens Matter. 2005 Jan 12;17(1):17-26. doi: 10.1088/0953-8984/17/1/002. Epub 2004 Dec 10.
In the first-principles calculations presented here we employ a density functional formalism using a pseudopotential plane-wave basis set in order to obtain the minimum energy configurations of various GaN(0001) 2 × 2 surfaces involving N atoms. The calculated formation energies of the 2 × 2 ideal model are compared with a previously proposed laterally contracted Ga bilayer model. We show how the order and stability of the different reconstructions are influenced by the choice of the standard 2 × 2 ideal or contracted bilayer model. On the basis of these results, we have characterized the effect on the adlayer surface of N segregation on the top of the surface, and the stability dependence on the number of substitutions for the different models employed. Our results predict that not all the adlayer structures containing nitrogen are unstable relative to the commonly considered N (H3) adatom configuration.
在本文所呈现的第一性原理计算中，我们采用密度泛函形式，使用赝势平面波基组，以获得包含氮原子的各种GaN(0001) 2×2表面的最低能量构型。将2×2理想模型的计算形成能与先前提出的横向收缩的Ga双层模型进行比较。我们展示了不同重构的有序性和稳定性如何受到标准2×2理想或收缩双层模型选择的影响。基于这些结果，我们表征了表面顶部氮偏析对吸附层表面的影响，以及所采用的不同模型中稳定性对替代原子数量的依赖性。我们的结果预测，并非所有含氮的吸附层结构相对于通常考虑的N(H3)吸附原子构型都是不稳定的。
