Characterization of nanoscale electronic structure in nonpolar GaN using scanning capacitance microscopy

Scanning capacitance microscopy is used to characterize nanoscale, local electronic structure in nonpolar n-type GaN grown in the a-plane orientation using lateral epitaxial overgrowth LEO . Analysis of the bias dependence of the scanning capacitance image contrast observed reveals the presence of a linear, positively charged feature aligned along the 1̄100 direction, extending from an LEO window region into the adjacent wing region and terminating a few microns into the wing region. Comparison of the scanning capacitance images with cathodoluminescence and transmission electron microscopy data, revealing the presence of line defects aligned along the 1̄100 direction that emerge from the window regions, indicates that this positively charged feature likely corresponds to a partial dislocation at the edge of a stacking fault. The observation of positive dislocation charge is striking in that studies of GaN grown in the polar c-plane orientation have predominantly revealed the presence only of negatively charged or electrically neutral dislocations. © 2008 American Institute of Physics. DOI: 10.1063/1.2828161