Jp. Sullivan et al., GIANT VARIATION IN SCHOTTKY-BARRIER HEIGHT OBSERVED IN THE CO SI SYSTEM/, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 11(4), 1993, pp. 1564-1570
In the literature, the Schottky barrier height (SBH) of Co/Si-related
interfaces consistently has been found to lie close to 0.65 eV on n-ty
pe Si. This apparent insensitivity of the SBH to the phase of the sili
cide and crystallographic orientation of the substrate had previously
been thought to support Fermi-level pinning mechanisms. We have, howev
er, through careful control Of molecular-beam epitaxy processing, grow
n single crystal type B CoSi2/Si (111) layers which exhibit a giant va
riation in SBH. CoSi2/Si(111) interfaces prepared by room temperature
and high temperature processing exhibit n-type SBHs close to 0.7 eV an
d p-type SBHs close to 0.45 eV, in good agreement with the SBHs of oth
er Co/Si-related interfaces. However, CoSi2/Si (111) interfaces prepar
ed by special layered growth techniques (here labeled as ''X'' interfa
ces) exhibit n-type SBHs less than 0.3 eV and p-type SBHs over 0.7 eV-
a difference of over 400 meV from the room temperature and high temper
ature interfaces. Other CoSi2/Si (111) interfaces prepared by differen
t processing conditions also often exhibit low n-type SBHs and elevate
d p-type SBHs, but over a somewhat smaller range. Plan-view and high-r
esolution transmission electron microscopy clearly indicated the exist
ence of structural defects or inhomogeneity in the low n-type SBH samp
les.