Using EELS to observe composition and electronic structure variations at dislocation cores in GaN

Abstract

Since the earliest observations of dislocations, the majority of the experimental transmission electron microscope studies have focused on understanding their structural properties. However, the extensive use of heteroepitaxial growth for binary, ternary and even more complex semiconductor systems on lattice mismatched substrates has also highlighted the importance of dislocations in determining the overall electronic properties of devices. Electron energy loss spectroscopy, when used in conjunction with atomic resolution Z-contrast imaging, provides the ability to quantify changes in both composition and electronic structure (and, therefore, electronic properties) that occur at dislocations in these semiconductor systems. In this paper, the principles behind atomic scale electron energy loss spectroscopy are described and work on their application to threading dislocations in GaN thin films performed over the last 3 years is reviewed.

Acknowledgements

Aspects of this work on edge dislocations were performed in collaboration with Stephen Pennycook and Yan Xin. The authors would also like to thank C. Kisielowski and C.-Y. Song in the National Center for Electron Microscopy (NCEM) at Lawrence Berkeley National Laboratory (LBNL) for sample preparation. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract No. DE-AC03-76SF0098 and Grant No. DE-FG02-03ER46057.

Notes

#Current address: Micro and Interfacial Sciences Department, Sandia National Laboratories, 7011 East Avenue, MS-9161, Livermore, CA 94550, USA.

Additional information

Notes on contributors

I. Arslan#

#Current address: Micro and Interfacial Sciences Department, Sandia National Laboratories, 7011 East Avenue, MS-9161, Livermore, CA 94550, USA.