Wachstum von Praseodymoxid auf Silizium (111) und (113)

Alternative gateoxide Pr2O3 : Growth characterization on Si (111)
and Si (113) Several investigations have been made to desricbe the
interface structure of this oxide on Si(111). These studies [Tarsa
et al., Müssig et al.] did show that the (001) plane of the
hexagonal phase of Pr2O3 is growning on the Si(111) surface. Last
year we reported about the p(1x1) observed in LEED. With gracing
incidence x-ray diffraction measurements, we can now explain the
bonding and positions of the Pr-Atoms and the orientation of the
oxide parallel to the surface. Several evidences lead to the
assumption, that the layer only occurs as a monolayer (= one unit
cell of hexagonal Pr2O3 bulk phase along the c vector). Thicker
layers observed in LEED, did not show any different
reconstructions. In situ GIXRD measurments of thicker layers are
underway. Postannealing up to 760°C of the thicker layers leads to
Island growth and forming PrSi2. The therby seen p(2x2)
reconstruction in LEED is formed from submonolayer coverage of Pr
on Si (111). The growth on Si(113) is reported the first time. The
depostion was made out of a tungsten or out of a mo-crucible at
500°C, like it was used for Si (111). After the depostion of 0.2 nm
of Pr2O3 one can observe a change in the LEED pattern from the
exhibited (3x1) or (3x2) reconstruction of Si (113) into a weak
(4x1) pattern. AFM pictures show an ordering in on dimension and
islands of triangular to trapezioid forms. The roughness is lower
than the one, seen on the p(2x2) reconstructed surface. First GIXD
measurements did not show any reconstructions peaks, which
indicates that the pattern seen in Leed is coming from the oxygen
ordering.