EBIC investigations of defect distribution in ELOG GaN films

The possibilities of the Electron Beam Induced Current (EBIC) method for the characterization of epitaxial lateral overgrowth (ELOG) GaN structures are demonstrated. The diffusion length and local donor concentrations in the structures studied are obtained by fitting the dependence of collected current in the EBIC mode on accelerating voltage with calculated one. It is shown that the local donor concentrations in the regions of lateral overgrowth measured by the EBIC are about three times lower than that in the vertically grown regions. This difference is observed in the structures with the donor concentration varying in the range from 10¹⁵ to 10¹⁷ cm^-3. These results could be ascribed to the anisotropy of Si incorporation efficiency during growth. A comparison of the EBIC results with the results of capacitance-voltage (C-V) profiling allows us to estimate the precision of EBIC dopant concentration measurements.