Density Functional Theory Study of the Stress Impact on Formation Enthalpy of Intrinsic Point Defect around Dopant Atom in Ge Crystal
Density Functional Theory Study of the Stress Impact on Formation Enthalpy of Intrinsic Point Defect around Dopant Atom in Ge Crystal
复制标题
应力对Ge晶体掺杂原子周围本征点缺陷生成焓影响的密度泛函理论研究
DOI：
10.1149/2.0131707jss
复制
发表时间：
2017
影响因子：
2.2
通讯作者：
and Koji Sueoka
中科院分区：
文献类型：
--
作者：
Shunta Yamaoka;Koji Kobayashi;and Koji Sueoka
在过去的十年中，单晶锗（Ge）层和结构与硅（Si）衬底的结合使用导致了对Ge缺陷研究的复兴。在Si晶体中，掺杂剂和应力影响本征点缺陷（空位V和自填隙I）参数，从而改变V和I的热平衡浓度。然而，由于缺乏实验数据，本征点缺陷浓度的控制尚未在Ge晶体中实现与Si晶体中相同的水平。采用密度泛函理论（DFT）计算了各向同性内外应力（σ in/σ ex）对Ge中掺杂原子（B、Ga、C、Sn和Sb）周围中性V和I的形成焓（Hf）的影响，并与Si的结果进行了比较.分析的结果有三个方面。第一，V（I）在完全Ge中的Hf随压力σ in的增大而减小，而V（I）在完全Ge中的Hf随压力σ ex的增大而减小。完整Ge晶体的应力影响大于完整Si晶体。第二，在Ge晶体中，Sn和Sb原子周围的V的Hf减小，而B、Ga和C原子周围的I的Hf减小。Ge晶体的掺杂剂影响小于Si晶体。压缩σ in降低（增加）Ge晶体中掺杂原子周围V（I）的Hf，与掺杂剂类型无关，而压缩σ ex对掺杂Ge晶体中V和I的Hf的影响小于压缩σ in。计算了掺锗单晶在生长过程中热应力作用下的总钒、碘在熔点处的热平衡浓度。
During the last decade, the use of single crystal germanium (Ge) layers and structures in combination with silicon (Si) substrates has led to a revival of defect research on Ge. In Si crystals, dopants and stresses affect the intrinsic point defect (vacancy V and self-interstitial I) parameters and thus change the thermal equilibrium concentrations of V and I. However, the control of intrinsic point defect concentrations has not yet been realized at the same level in Ge crystals as in Si crystals due to the lack of experimental data. In this study, we have used density functional theory (DFT) calculations to evaluate the effect of isotropic internal/external stress (σ in/σ ex) on the formation enthalpy (H f) of neutral V and I around dopant (B, Ga, C, Sn, and Sb) atom in Ge and compared the results with those for Si. The results of the analysis are threefold. First, H f of V (I) in perfect Ge is decreased (increased) by compressive σ in while H f of V (I) in perfect Ge is increased (decreased) by compressive σ ex, ie, hydrostatic pressure. The stress impact for perfect Ge crystals is larger than that for perfect Si crystals. Second, H f of V around Sn and Sb atoms decrease while H f of I around B, Ga, and C atoms decrease in Ge crystals. The dopant impact for Ge crystals is smaller than that for Si crystals. Third, the compressive σ in decreases (increases) H f of V (I) around dopant atom in Ge crystals independent of the dopant type while the σ ex has a smaller effect on H f of V and I in doped Ge crystals than the σ in. The thermal equilibrium concentrations of total V and I at the melting point of doped Ge under the thermal stresses during the crystal growth were also evaluated.