High spatial resolution picosecond cathodoluminescence of InGaN quantum wells

Abstract

The authors have studied In x Ga 1−x N / GaN ͑x Ϸ 15% ͒ quantum wells ͑QWs͒ using atomic force microscopy ͑AFM͒ and picosecond time resolved cathodoluminescence ͑pTRCL͒ measurements. They observed a contrast inversion between monochromatic CL maps corresponding to the high energy side ͑3.13 eV͒ and the low energy side ͑3.07 eV͒ of the QW luminescence peak. In perfect correlation with CL images, AFM images clearly show regions where the QW thickness almost decreases to zero. Pronounced spectral diffusion from high energy thinner regions to low energy thicker regions is observed in pTRCL, providing a possible explanation for the hindering of nonradiative recombination at dislocations.

Exciton dynamics at a single dislocation in GaN probed by picosecond time-resolved cathodoluminescence

“…[13][14][15] Here, thanks to a picosecond TR-CL setup combining high temporal (<20 ps), spatial ($50 nm for the secondary electron image), and spectral ($3 meV) resolutions, we investigate the exciton dynamics at T ¼ 10 K on a single dislocation in bulk GaN grown by MOVPE.…”

Exciton localization on basal stacking faults in a-plane epitaxial lateral overgrown GaN grown by hydride vapor phase epitaxy

“…One may be tempted to attribute this emission to carriers that would be scattered from the excitation spot to the regions where intense BSF recombination is observed. However, the estimation of the excitation volume for our 20 kV electron beam with Monte Carlo simulations, 15 combined with the experimental determination of the diffusion length of excited carriers in GaN, 16 shows that carriers only diffuse ϳ1.5 m away from the excitation spot.…”

Photon bunching reveals single-electron cathodoluminescence excitation efficiency in InGaN quantum wells

“…DOI: 10.1103/PhysRevB.96. 035308 Cathodoluminescence spectroscopy (CL) is a well-known technique for the characterization of semiconductor materials [1][2][3][4][5][6]. In CL, a high-energy electron beam in a scanning electron microscope (SEM) excites a material and generates luminescence that is collected and analyzed.…”