Journal
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
Volume 258, Issue 11, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/pssb.202100358
Keywords
AlGaN; cathodoluminescence; dark spots; internal quantum efficiency; threading dislocations
Categories
Funding
- German Federal Ministry of Education and Research (BMBF) within the Advanced UV for Life consortium [03ZZ0134B]
- Projekt DEAL
Ask authors/readers for more resources
Threading dislocations in c-plane (Al,Ga)N layers are surrounded by dark spots which reduce light generation efficiency. The diameter of dark spots is observed to vary with temperature in AlGaN and GaN, with different effects on emission energy mapping. Charge carrier localization and temperature-dependent excitation volume are dominant in AlGaN, while charge carrier diffusion limited by phonon scattering plays a key role in GaN.
Threading dislocations in c-plane (Al,Ga)N layers are surrounded by areas with reduced light generation efficiency, called dark spots. These areas are observable in luminescence measurements with spatial resolution in the submicrometer range. Dark spots reduce the internal quantum efficiency in single layers and light-emitting devices. In cathodoluminescence measurements, the diameter of dark spots (full width at half maximum [FWHM]) is observed to be 200-250 nm for GaN. It decreases by 30-60% for AlxGa1-xN with x approximate to 0.5. Furthermore, the dark spot diameter increases with increasing temperature from 83 to 300 K in AlGaN, whereas it decreases in GaN. Emission energy mappings around dark spots become less smooth and show sharper features on submicrometer scales at low temperature for AlGaN and, on the contrary, at high temperature for GaN. It is concluded that charge carrier localization dominates the temperature dependence of dark spot diameters and of the emission energy distribution around threading dislocations in AlGaN, whereas the temperature-dependent excitation volume in cathodoluminescence and charge carrier diffusion limited by phonon scattering are the dominant effects in GaN. Consequently, with increasing temperature, nonradiative recombination related to threading dislocations extends to wider regions in AlGaN, whereas it becomes spatially limited in GaN.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available