Nanoscale cathodoluminescence of stacking faults and partial dislocations in a‐plane GaN

Abstract

In GaN, the basal plane stacking fault type I1 is a two‐dimensional defect characterized by a cubic inclusion within the wurtzite structure. Excitons are bound at the BSF I1 similar to the localization in a quantum well heterostructure leading to an efficient radiative recombination. In this study, we present the optical and structural properties of basal plane stacking faults occurrent in silicon doped a‐plane GaN layer by means of highly spatially resolved cathodoluminescence spectroscopy performed in a scanning transmission electron microscope. Drastically reduced panchromatic intensity in the vicinity of partial dislocations terminating the stacking faults, points to their non‐radiative character. Originating from intersection of two‐dimensional defects, the emission at 379.6 nm could be attributed to optically active stair‐rod dislocations.

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“…The most distinct feature of the panchromatic intensity map in Figure b is the appearance of a dark contrast loop indicating emission quenching. As the shape of the loop matches with the boundary of the defect, these results suggest that the Drum 8/4/8/4 ring configuration displays similar optical properties to TDs, which have been demonstrated to act as nonradiative recombination sites. , Both Urban et al and Schmidt et al have previously performed nano-CL in the [110] direction on BSFs in GaN and for the latter, attributed decreased CL intensity with the bounding partial dislocations. , Here, however, our high magnification characterization from the [0001] direction allows us to link the optical properties with the exact PSF core structure. Within the BSF, away from its boundaries with the pristine crystal, the panchromatic map exhibits little to no emission dip as presented in the line scan of the signal across the BSF (Figure c).…”

“…The most distinct feature of the panchromatic intensity map in Figure 5b is the appearance of a dark contrast loop indicating emission quenching. As the shape of the loop matches with the boundary of the defect, these 38,39 Here, however, our high magnification characterization from the [0001] direction allows us to link the optical properties with the exact PSF core structure. Within the BSF, away from its boundaries with the pristine crystal, the panchromatic map exhibits little to no emission dip as presented in the line scan of the signal across the BSF (Figure 5c).…”