Carrier Mobility Enhancement of Tensile Strained Si and SiGe Nanowires via Surface Defect Engineering
journal contribution
posted on 2015-11-11, 00:00 authored by J. W. Ma, W. J. Lee, J. M. Bae, K. S. Jeong, S. H. Oh, J. H. Kim, S.-H. Kim, J.-H. Seo, J.-P. Ahn, H. Kim, M.-H. ChoChanges in the carrier mobility of
tensile strained Si and SiGe nanowires (NWs) were examined using an
electrical push-to-pull device (E-PTP, Hysitron). The changes were
found to be closely related to the chemical structure at the surface,
likely defect states. As tensile strain is increased, the resistivity
of SiGe NWs deceases in a linear manner. However, the corresponding
values for Si NWs increased with increasing tensile strain, which
is closely related to broken bonds induced by defects at the NW surface.
Broken bonds at the surface, which communicate with the defect state
of Si are critically altered when Ge is incorporated in Si NW. In
addition, the number of defects could be significantly decreased in
Si NWs by incorporating a surface passivated Al2O3 layer, which removes broken bonds, resulting in a proportional decrease
in the resistivity of Si NWs with increasing strain. Moreover, the
presence of a passivation layer dramatically increases the extent
of fracture strain in NWs, and a significant enhancement in mobility
of about 2.6 times was observed for a tensile strain of 5.7%.
