Giant enhancement of n-type carrier mobility in highly strained germanium nanostructures
Fahy, Stephen B.
American Institute of Physics Publishing
First-principles electronic structure methods are used to predict the rate of n-type carrier scattering due to phonons in highly-strained Ge. We show that strains achievable in nanoscale structures, where Ge becomes a direct bandgap semiconductor, cause the phonon-limited mobility to be enhanced by hundreds of times that of unstrained Ge, and over a thousand times that of Si. This makes highly tensile strained Ge a most promising material for the construction of channels in CMOS devices, as well as for Si-based photonic applications. Biaxial (001) strain achieves mobility enhancements of 100 to 1000 with strains over 2%. Low temperature mobility can be increased by even larger factors. Second order terms in the deformation potential of the Gamma valley are found to be important in this mobility enhancement. Although they are modified by shifts in the conduction band valleys, which are caused by carrier quantum confinement, these mobility enhancements persist in strained nanostructures down to sizes of 20 nm.
Phonons , Ab initio calculations , Nanostructured materials , Carrier mobility , Elemental semiconductors , Germanium , Conduction bands
MURPHY-ARMANDO, F. & FAHY, S. B. 2011. Giant enhancement of n-type carrier mobility in highly strained germanium nanostructures. Journal of Applied Physics, 109, 113703. doi:10.1063/1.3590334
© 2011, AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Journal of Journal of Applied Physics, 109, 113703. (2011) and may be found at http://scitation.aip.org/content/aip/journal/jap/109/11/10.1063/1.3590334