Strain-modulated electronic properties of Ge nanowires

A first-principles study

Paul Logan, Xihong Peng

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

We used density-functional theory based first-principles simulations to study the effects of uniaxial strain and quantum confinement on the electronic properties of germanium nanowires along the [110] direction, such as the energy gap and the effective masses of the electron and hole. The diameters of the nanowires being studied are up to 50. As shown in our calculations, the Ge [110] nanowires possess a direct band gap, in contrast to the nature of an indirect band gap in bulk. We discovered that the band gap and the effective masses of charge carries can be modulated by applying uniaxial strain to the nanowires. These strain modulations are size dependent. For a smaller wire (∼12), the band gap is almost a linear function of strain; compressive strain increases the gap while tensile strain reduces the gap. For a larger wire (20-50), the variation in the band gap with respect to strain shows nearly parabolic behavior: compressive strain beyond -1% also reduces the gap. In addition, our studies showed that strain affects effective masses of the electron and hole very differently. The effective mass of the hole increases with a tensile strain while the effective mass of the electron increases with a compressive strain. Our results suggested both strain and size can be used to tune the band structures of nanowires, which may help in design of future nanoelectronic devices. We also discussed our results by applying the tight-binding model.

Original languageEnglish (US)
Article number115322
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume80
Issue number11
DOIs
StatePublished - Sep 24 2009

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Electronic properties
Nanowires
nanowires
electronics
Energy gap
axial strain
Tensile strain
wire
Electrons
electrons
Wire
Germanium
Quantum confinement
Nanoelectronics
germanium
Band structure
Density functional theory
density functional theory
modulation
Modulation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Strain-modulated electronic properties of Ge nanowires : A first-principles study. / Logan, Paul; Peng, Xihong.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 80, No. 11, 115322, 24.09.2009.

Research output: Contribution to journalArticle

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