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Optical Properties of Thin-Film SrTiO3 on Si Grown by MBE

Published online by Cambridge University Press:  10 February 2011

Stefan Zollner ,
A.A. Demkov ,
Ran Liu ,
J.A. Curless ,
Z. Yu ,
J. Ramdani  and
R. Droopad
Stefan Zollner
Affiliation:
Motorola Semiconductor Products Sector, Materials and Structures Laboratory, Mesa, AZ
A.A. Demkov
Affiliation:
Motorola Semiconductor Products Sector, Materials and Structures Laboratory, Mesa, AZ
Ran Liu
Affiliation:
Motorola Semiconductor Products Sector, Materials and Structures Laboratory, Mesa, AZ
J.A. Curless
Affiliation:
Physical Sciences Research Laboratories, Motorola Labs, Tempe, AZ 85284
Z. Yu
Affiliation:
Physical Sciences Research Laboratories, Motorola Labs, Tempe, AZ 85284
J. Ramdani
Affiliation:
Physical Sciences Research Laboratories, Motorola Labs, Tempe, AZ 85284
R. Droopad
Affiliation:
Physical Sciences Research Laboratories, Motorola Labs, Tempe, AZ 85284
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Abstract

Oxides with perovskite crystal structure such as SrTiO3 are important candidates for ultrathin gate oxides because of their large DC dielectric constant. When SrTiO3 is deposited directly on Si, an amorphous non-stoichiometric interfacial layer is usually formed during the later stages of growth, which reduces the specific capacitance and is therefore undesirable. We have performed deep-UV spectroscopic ellipsometry measurements from 0.7 to 6.6 eV of SrTiO3 films grown on Si by MBE. This technique is very well suited to determine the thickness of SrTiO3 films between 75 and 200 Å. For thinner films, refractive index and thickness cannot be determined independently. Ellipsometry measures the total thickness (SrTiO3 plus amorphous interfacial layer). There is no signature in the data that can be used to determine the SrTiO3 and interfacial layer thicknesses independently. We find that the effective refractive index (averaged over the crystalline SrTiO3 and the interfacial layer) decreases with decreasing thickness due to the increasing importance of the interfacial layer, but the overall critical-points due to interband transitions are not eliminated, therefore the electronic structure stays mostly intact.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 619: Symposium L – Recent Developments in Oxide & Metal Epitaxy – Theory… , 2000 , 167
Copyright
Copyright © Materials Research Society 2000

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References

REFERENCES

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