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Molecular Dynamics Simulation of Germanium Nanoparticles

Published online by Cambridge University Press:  15 February 2011

Sang H. Yang
Affiliation:
Air Force Research Laboratory, Material and Manufacturing Directorate, WPAFB, OH 45433, USA
Rajiv J. Berry
Affiliation:
Air Force Research Laboratory, Material and Manufacturing Directorate, WPAFB, OH 45433, USA
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Abstract

Nanoparticles are known to melt at temperatures well below the bulk melting point. This behavior is being exploited for the recrystallization of Germanium to form large-grain semiconductor thin films on flexible and low temperature substrates. The melting of Ge nanoparticles as a function of size was investigated using the ab-initio Harris functional method of density functional theory (DFT).

The DFT code was initially evaluated for its ability to predict the bulk properties of crystalline Ge. A conjugate gradient method was employed for minimizing the multiphase atomic positional parameters of the diamond, BC8 and ST12 structures. The computed lattice constants, bulk moduli, and internal atomic positional parameters were found to agree well with other calculations and with reported experimental results.

A constant temperature Nose-Hoover thermostat was added to the DFT code in order to compute thermal properties via molecular dynamics. The simulations were tested on a 13-atom Ge cluster, which was found to melt at 820 K. Further heating resulted in the cluster breaking up into two smaller clusters, which remained stable up to 1300K.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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