Effect of strain on the appearance of subcritical nuclei of ge nanohuts on Si(001).
Real-time scanning tunneling microscopy observations of nucleation and heteroepitaxial growth of Ge nanocrystals (from germane) on Si(001) indicate that in the absence of Si-Ge intermixing the formation of full hut cluster islands is preceded by the nucleation of "subcritical" nuclei consisting of two adjacent truncated tetrahedral pyramids, which, upon unification, form a tiny square-based pyramidal "critical nucleus" It is suggested that such a precursor aids in surpassing the nucleation barrier and that the recently reported gradual faceting of prepyramids is characteristic of only Ge(Si) alloys.
Goldfarb
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Department of Solid Mechanics, Materials and Systems, School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel.