Characterization of nanoscale electronic structure in nonpolar GaNusing 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 [ I 100] 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 [(1) over bar 100] 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. (c) 2008 American Institute of Physics.