C incorporation in epitaxial Ge1-yCy layers grown on Ge(001): An ab initio study
C incorporation in epitaxial Ge1-yCy layers grown on Ge(001): An ab initio study
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在 Ge(001) 上生长的外延 Ge1-yCy 层中的 C 掺入：从头算研究
DOI：
10.1103/physrevb.62.r7723
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发表时间：
2000
影响因子：
3.7
通讯作者：
J. Greene
中科院分区：
文献类型：
--
作者：
D. Gall;J. D’Arcy;J. Greene
采用广义梯度近似的从头算密度泛函计算已用于确定在 Ge ~001! 上生长的完全相干 Ge 12yCy 层中与不同 C 晶格位点配置相关的形成能 U 和应变。使用应变 64 原子超晶胞的计算表明，取代 C（U52.40 eV）是最稳定的构型，每种构型仅涉及一个 C 原子。以键为中心的间隙结构和Ge-C分裂间隙结构的形成能分别高2.9和1.78 eV。然而，@001# 取向的 C 对和 C 三联体甚至比取代的 C 更稳定，每个 C 原子稳定 0.17 和 0.80 eV，这表明在 Ge12yCy 生长过程中 C 原子有很强的聚集倾向。计算出的 C 引起的应变系数为解释 Ge 12yCy X 射线衍射结果和宏观应变测量提供了见解。
Ab initio density-functional calculations, employing the generalized-gradient approximation, have been used to determine formation energies U and the strain associated with different C lattice site configurations in fully coherent Ge 12yCy layers grown on Ge ~001!. Calculations using strained 64-atom supercells show that substitutional C, for whichU52.40 eV, is the most stable configuration involving only one C atom per configuration. The bond-centered interstitial and the Ge-C split interstitial configurations have formation energies which are 2.9 and 1.78 eV higher, respectively. However, @001#-oriented C pairs and C triplets are even more stable than substitutional C, by 0.17 and 0.80 eV per C atom, indicating a strong tendency for C atoms to cluster during Ge12yCy growth. Calculated C-induced strain coefficients provide insight for interpreting Ge 12yCy x-ray diffraction results and macroscopic strain measurements.