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.
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7 January 2019
Research Article|
January 07 2019
Carrier localization structure combined with current micropaths in AlGaN quantum wells grown on an AlN template with macrosteps
K. Kojima;
K. Kojima
a)
1
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
, Aoba, Sendai 980-8577, Japan
a)Author to whom correspondence should be addressed: [email protected]
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Y. Nagasawa;
Y. Nagasawa
2
UV Craftory Co., Ltd., Fujimidai
, Chikusa, Nagoya 464-0015, Japan
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A. Hirano;
A. Hirano
2
UV Craftory Co., Ltd., Fujimidai
, Chikusa, Nagoya 464-0015, Japan
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M. Ippommatsu;
M. Ippommatsu
2
UV Craftory Co., Ltd., Fujimidai
, Chikusa, Nagoya 464-0015, Japan
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Y. Honda;
Y. Honda
3
Institute of Materials and Systems for Sustainability, Nagoya University
, Furo, Chikusa, Nagoya 464-8601, Japan
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H. Amano;
H. Amano
3
Institute of Materials and Systems for Sustainability, Nagoya University
, Furo, Chikusa, Nagoya 464-8601, Japan
4
Akasaki Research Center, Nagoya University
, Furo, Chikusa, Nagoya 464-8601, Japan
5
Venture Business Laboratory, Nagoya University
, Furo, Chikusa, Nagoya 464-8601, Japan
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I. Akasaki;
I. Akasaki
4
Akasaki Research Center, Nagoya University
, Furo, Chikusa, Nagoya 464-8601, Japan
6
Meijo University, Shiogamaguchi
, Tempaku, Nagoya 468-8502, Japan
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S. F. Chichibu
S. F. Chichibu
1
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
, Aoba, Sendai 980-8577, Japan
3
Institute of Materials and Systems for Sustainability, Nagoya University
, Furo, Chikusa, Nagoya 464-8601, Japan
7
Research Center for Integrated Quantum Electronics, Hokkaido University
, Kita, Sapporo 060-0813, Japan
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a)Author to whom correspondence should be addressed: [email protected]
Appl. Phys. Lett. 114, 011102 (2019)
Article history
Received:
September 30 2018
Accepted:
December 13 2018
Citation
K. Kojima, Y. Nagasawa, A. Hirano, M. Ippommatsu, Y. Honda, H. Amano, I. Akasaki, S. F. Chichibu; Carrier localization structure combined with current micropaths in AlGaN quantum wells grown on an AlN template with macrosteps. Appl. Phys. Lett. 7 January 2019; 114 (1): 011102. https://doi.org/10.1063/1.5063735
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