Abstract
This study reports the observation of six different zincblende compound semiconductors in [110] projection using large-collection-angle bright-field (LABF) imaging with an aberration-corrected scanning transmission electron microscope. Phase contrast is completely suppressed when the collection semi-angle is set equal to the convergence semi-angle and there are no reversals in image contrast with changes in defocus or thickness. The optimum focus for imaging closely separated pairs of atomic columns ('dumbbells') is unique and easily recognized, and the positions of atomic columns occupied by heavier atoms always have darker intensity than those occupied by lighter atoms. Thus, the crystal polarity of compound semiconductors can be determined unambiguously. Moreover, it is concluded that the LABF imaging mode will be highly beneficial for studying other more complicated heterostructures at the atomic scale.
| Original language | English (US) |
|---|---|
| Article number | 094002 |
| Journal | Semiconductor Science and Technology |
| Volume | 31 |
| Issue number | 9 |
| DOIs | |
| State | Published - Jul 25 2016 |
Keywords
- aberration-corrected electron microscopy
- compound semiconductor
- crystal polarity
- large-angle bright-field imaging
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry