Transcript Document

The initial growth-stages of SrTiO3 on Si(001):
first principles studies
Han Han and J. G. Che
Department of Physics, Fudan University
Ferroelectrical materials in contact with semiconductors has been touted as very useful non-volatile memories and smart transistors.
SrTiO3(001)/Si(001) structure is a promising candidate due to its high dielectric constant and the relatively small lattice mismatch with silicon
lattice. Questions also arised since experiments have shown that it is not so easy to establish an abrupt SrTiO3/Si interface due to the easy
formation of oxide of Si and other defectes by the high reactivity of Si. We demonstrate the mechanism of the initial growth-stages of SrTiO3
on Si(001) structures by an ab-initio study here.
I. Background:
Some STO(001)/Si(001) interfaces are listed
in the left figure in different years.
Until recent years, SrTiO3(STO) thin films
have been grown on Si (100) single crystals
without silicon oxide interfacial layers
successfully. The right figure site from
SCIENCE VOL 324 17 (2009):
written and imaged on a 6 ML SrTiO3/Si
sample by PFM.
II. The silicon surface and
itsinterface with SiO2:
III. Sr0.5O/Si interface:
top view of clean and oxidized Si(001)
surface structure with three kinds of
O absorption site noted on it
The calculation model at
NATURE 427,53(2004) to
predict a sharp STO/Si
interface (figure on top). The
most stable structure in this
model by our calculation
( figure on bottom).
2 1
SiO2/Si interfacial structure ( sited
from PRL 84, 19(2000) )
IV. SrO/Si interface: the role of Sr
V. The effect of double bond:
More SrO and TiO2
layers are deposited to
form STO/Si sharp
interface:
The PES( potential energy
surface) for atomic oxygen on a
1MLSr-covered Si(001) surface.
The energetics find by
NEB(Nudged elastic band )
method calculation between sharp
and oxdized interfacial structures.
The 1st layer SrO on Si:
PDOS for atoms at interface: a double
bonding between Si and O.(a)for 1MLSrO
on Si (b) for 3ucSTO on Si