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Carrier localization structure combined with current micropaths in AlGaN quantum wells grown on an AlN template with macrosteps
- Source :
- Applied Physics Letters. 114:011102
- Publication Year :
- 2019
- Publisher :
- AIP Publishing, 2019.
-
Abstract
- The microscopic structural and optical characteristics of AlGaN-based light-emitting diodes grown on AlN templates with macrosteps were evaluated. Cross-sectional transmission electron microscopy in the high-angle annular dark field scanning mode and microscopic energy dispersive X-ray spectroscopy reveal that the AlGaN cladding layer under the AlGaN quantum wells (QWs) has microscopic compositional modulations originating from the macrosteps at the AlN template surface. The Ga-rich oblique zones in the cladding layer likely behave as current micropaths. These micropaths are connected to the carrier localization structure, which is formed by the modulation of both the well widths and the compositions of the QWs. In-plane spatially-resolved cathodoluminescence (CL) spectroscopy indicated significant inhomogeneity of the CL characteristics: the brighter emission with a lower peak photon energy confirms the existence of the carrier localization structure in the QWs. Carrier localization in the QWs along with the current micropaths in the AlGaN cladding layer appears to increase the external quantum efficiency of AlGaN LEDs.
- Subjects :
- 010302 applied physics
Materials science
Physics and Astronomy (miscellaneous)
business.industry
Cathodoluminescence
02 engineering and technology
021001 nanoscience & nanotechnology
Cladding (fiber optics)
01 natural sciences
Dark field microscopy
law.invention
law
Transmission electron microscopy
0103 physical sciences
Optoelectronics
Quantum efficiency
0210 nano-technology
Spectroscopy
business
Quantum well
Light-emitting diode
Subjects
Details
- ISSN :
- 10773118 and 00036951
- Volume :
- 114
- Database :
- OpenAIRE
- Journal :
- Applied Physics Letters
- Accession number :
- edsair.doi...........eb3c451bb5734e848396ba890638f8b3