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Germanium Nanocrystals Embedded in Sapphire

Published online by Cambridge University Press:  01 February 2011

Q. Xu
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, U.S.A.
I.D. Sharp
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, U.S.A.
C.Y. Liao
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, U.S.A.
D. O. Yi
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. Applied Science and Technology Group, University of California, Berkeley, CA 94720, U.S.A.
J.W. Ager III
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A.
J.W. Beeman
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A.
K.M. Yu
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A.
D. C. Chrzan
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, U.S.A.
E.E. Haller
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, U.S.A.
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Abstract

74Ge nanocrystals are formed in a sapphire matrix by ion implantation followed by thermal annealing. Transmission electron microscopy (TEM) of as-grown samples reveals that the nanocrystals are faceted and have a bi-modal size distribution. Notably, the matrix remains crystalline despite the large implantation dose and corresponding damage. Embedded nanocrystals experience large compressive stress relative to bulk, as measured by Raman spectroscopy of the zone center optical phonon. In contrast, ion-beam-synthesized nanocrystals embedded in silica are observed to be spherical and experience considerably lower stresses. Also, in situ TEM reveals that nanocrystals embedded in sapphire melt very close to the bulk melting point (Tm= 936 °C) whereas those embedded in silica exhibit a significant melting point hysteresis around Tm.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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