Comparison of semi-empirical potential functions for silicon and germanium

Abstract

We report the results of investigations into the behavior of the crystalline and liquid phases of silicon and germanium as they are modeled by the Tersoff and modified-embedded-atom-method (MEAM) potentials. The structure of the solid-liquid interface produced by each potential is determined, as are the melting points corresponding to each potential model. The equilibrium properties of both crystalline and liquid silicon and germanium as modeled by the Tersoff and MEAM potentials are then presented.The Tersoff potential is found to overestimate greatly the melting point of both silicon and germanium, while the MEAM underestimates the melting point of silicon by approximately 15%%uo. The MEAM does not yield a stable liquid phase of germanium. Both potential models produce a (100) solid-liquid interface for both semiconductors that is rough, while the (111) interface is found to be atomically smooth.The Tersoff potential yields an amorphous phase for both silicon and germanium, but efforts to produce an amorphous MEAM phase were unsuccessful. Rapid solidification of MEAM silicon produced unphysical regrowth velocities.

In situHigh-Energy X-Ray Diffraction Study of the Local Structure of Supercooled Liquid Si

“…The second peak in G r is actually composed of two subpeaks, at approximately 3.45 and 4.0 Å . We note that a similar distribution of peaks was predicted from simulation studies using the Stillinger-Weber potential [3,14,15]. With supercooling, both subpeaks in G r increase in intensity, signaling a change in the local order of the liquid upon cooling, consistent with the changes observed in S q .…”

Molecular dynamics simulations of damage production by thermal spikes in Ge

“…33 The Tersoff inter-atomic potential notably overestimates the melting temperature. Reported values in the literature obtained with this potential by different methods range from 2554 K to 3300 K for Ge 34,35 and from 2000 K to 3000 K for Si. 14,19,34,36,37 The Stillinger-Weber potential, initially only proposed for Si, was adapted by Ding et al to model Ge, obtaining a very high melting temperature.…”

“…Reported values in the literature obtained with this potential by different methods range from 2554 K to 3300 K for Ge 34,35 and from 2000 K to 3000 K for Si. 14,19,34,36,37 The Stillinger-Weber potential, initially only proposed for Si, was adapted by Ding et al to model Ge, obtaining a very high melting temperature. 27 Using the formulation of Ding et al as a starting point, some authors have developed Stillinger-Weber-type potentials to obtain a more accurate description of the melting of Ge, either focusing on reproducing the actual melting temperature 14 or the right cohesive energy.…”

Detailed microscopic analysis of self-interstitial aggregation in silicon. II. Thermodynamic analysis of single clusters

“…Moreover, the energy minimization for each configuration also was performed at constant volume, which generally leads to the generation of additional tension in the final structures because the average lattice parameter is larger at high temperature than it is at zero temperature. 53,54 In order to assess whether these assumptions materially affect the results presented in the previous sections, we repeated the calculations of the PDF for the four-interstitial cluster at 1100 K within the NPT ensemble. In these calculations, all energy minimizations also were performed at constant pressure ͑i.e., the simulation box was allowed to change size during energy minimization͒ in order to ensure that the final formation enthalpy was defined at the intended pressure.…”