344
11 Surfaces
Fig. 11.6 STM image of
Si(001) surface with an
off-cut θ = 0.5 ◦ . Adapted
from [1069]
(a)
10nm (b)
Fig. 11.7 a STM images a ZnO(00.1) O-terminated surface, left (right) panel with zero (about 1.3 ◦ ) off-cut, exhibiting
monolayer step heights of 0.27 nm. a LEED pattern of such surface (recorded at 70 eV). Adapted from [1070]
A similar example is the Zn(00.1) surface. The found step height of the monoatomic steps is 0.27 nm
and corresponds c/2 [1070]. The terrace width is about 12 nm (Fig. 11.7a), yielding an off-cut (11.2)
of about 1.3
◦ . The surface pattern shows triangular features in two orientations, rotated by 60
◦ . The
3m symmetry of the surface, although the first monolayer has 6 m point symmetry (Table 11.1), occurs
in two domains rotated against each other by 60
◦ . The LEED pattern from each individual terrace
is expected to have three-fold symmetry; the mixed character of the surface yields a six-fold pattern
(Fig. 11.7b).
Steps can gather and form step bunches with a height much larger than a monolayer (Fig. 11.8).
Faceting of higher index planes occurs when it is energetically favorable to form alternating facets of
low energy low index planes, for example Si(223) exhibits periodic ridges with (111) and (113) facets
[1071]. The faceting of a surface close to (113), exhibiting smooth (113) and rough (114) planes, is
depicted in Fig. 11.9.
11 Surfaces
Fig. 11.6 STM image of
Si(001) surface with an
off-cut θ = 0.5 ◦ . Adapted
from [1069]
(a)
10nm (b)
Fig. 11.7 a STM images a ZnO(00.1) O-terminated surface, left (right) panel with zero (about 1.3 ◦ ) off-cut, exhibiting
monolayer step heights of 0.27 nm. a LEED pattern of such surface (recorded at 70 eV). Adapted from [1070]
A similar example is the Zn(00.1) surface. The found step height of the monoatomic steps is 0.27 nm
and corresponds c/2 [1070]. The terrace width is about 12 nm (Fig. 11.7a), yielding an off-cut (11.2)
of about 1.3
◦ . The surface pattern shows triangular features in two orientations, rotated by 60
◦ . The
3m symmetry of the surface, although the first monolayer has 6 m point symmetry (Table 11.1), occurs
in two domains rotated against each other by 60
◦ . The LEED pattern from each individual terrace
is expected to have three-fold symmetry; the mixed character of the surface yields a six-fold pattern
(Fig. 11.7b).
Steps can gather and form step bunches with a height much larger than a monolayer (Fig. 11.8).
Faceting of higher index planes occurs when it is energetically favorable to form alternating facets of
low energy low index planes, for example Si(223) exhibits periodic ridges with (111) and (113) facets
[1071]. The faceting of a surface close to (113), exhibiting smooth (113) and rough (114) planes, is
depicted in Fig. 11.9.