Strain field mapping of dislocations in a Ge/Si heterostructure

PLoS One. 2013 Apr 23;8(4):e62672. doi: 10.1371/journal.pone.0062672. Print 2013.

Abstract

Ge/Si heterostructure with fully strain-relaxed Ge film was grown on a Si (001) substrate by using a two-step process by ultra-high vacuum chemical vapor deposition. The dislocations in the Ge/Si heterostructure were experimentally investigated by high-resolution transmission electron microscopy (HRTEM). The dislocations at the Ge/Si interface were identified to be 90° full-edge dislocations, which are the most efficient way for obtaining a fully relaxed Ge film. The only defect found in the Ge epitaxial film was a 60° dislocation. The nanoscale strain field of the dislocations was mapped by geometric phase analysis technique from the HRTEM image. The strain field around the edge component of the 60° dislocation core was compared with those of the Peierls-Nabarro and Foreman dislocation models. Comparison results show that the Foreman model with a = 1.5 can describe appropriately the strain field around the edge component of a 60° dislocation core in a relaxed Ge film on a Si substrate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Germanium / chemistry*
  • Microscopy, Electron, Transmission
  • Models, Chemical
  • Nanostructures / chemistry*
  • Nanostructures / ultrastructure
  • Silicon / chemistry*

Substances

  • Germanium
  • Silicon

Grants and funding

This work was supported by the National Natural Science Foundation of China Nos. 11062008, 11272142 and 61036003. This work was also supported by the Program for New Century Excellent Talents in University No. NCET-10-0909, the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.