Germanium Nanocrystals Embedded in Sapphire.

Xu, Q. ; Sharp, I. D. ; Liao, C. Y. ; Yi, D. O. ; Ager, J. W. ; Beeman, J. W. ; Yu, K. M. ; Chrzan, D. C. ; Haller, E. E.

Technical Information Center Oak Ridge Tennessee

关键词: Nanocrystals;    Germanium;    Sapphire;    Ion implantation;    Thermal annealing;   

RP-ID  :  DE2005861519

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

(sup 74)Ge 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 deg C) whereas those embedded in silica exhibit a significant melting point hysteresis around T(sub m).