Published online by Cambridge University Press: 02 July 2020
GaN-based materials hold promise for electronic and optical applications. Lacking a suitable lattice matched substrate, microstructural investigation by electron microscopy has become an important player in the development of these materials. Electron microscopy investigations vary from standard defect analysis, to polarity determination, to evaluation of electronic structure. To date, no evidence of electron beam damage has been reported.
For this experiment, the beam current from the Cornell University VG501 lOOkV STEM was approximately 0.3nA. During acquisition of multiple PEEL spectra of the N K-edge, the intensity of the core loss decreased and eventually disappeared due to electron beam induced damage. Damage is a function of dose. Thus observation of damage is dependent upon magnification and thickness, i.e., electron dose and fractional change in signal.
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4. This work was supported by the Office of Naval Research under MURI Contract No. N00014-96- 1-1223 monitored by John C. Zolper. Dr. The authors would like to acknowledge: William Schaff Dr. and Michael Murphy for the GaN sample and Malcom Thomas and Earl Kirkland Dr. for technical support and helpful discussions.Google Scholar