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Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers

To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type Al(x)Ga((1−x))N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, holes are depleted in the EB...

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Autores principales: Jain, Barsha, Velpula, Ravi Teja, Patel, Moulik, Sadaf, Sharif Md., Nguyen, Hieu Pham Trung
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003968/
https://www.ncbi.nlm.nih.gov/pubmed/33801072
http://dx.doi.org/10.3390/mi12030334
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author Jain, Barsha
Velpula, Ravi Teja
Patel, Moulik
Sadaf, Sharif Md.
Nguyen, Hieu Pham Trung
author_facet Jain, Barsha
Velpula, Ravi Teja
Patel, Moulik
Sadaf, Sharif Md.
Nguyen, Hieu Pham Trung
author_sort Jain, Barsha
collection PubMed
description To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type Al(x)Ga((1−x))N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, holes are depleted in the EBL due to the formation of positive sheet polarization charges at the heterointerface of the last quantum barrier (QB)/EBL. Subsequently, the hole injection efficiency of the LED is severely limited. In this regard, we propose an EBL-free AlGaN deep UV LED structure using graded staircase quantum barriers (GSQBs) instead of conventional QBs without affecting the hole injection efficiency. The reported structure exhibits significantly reduced thermal velocity and mean free path of electrons in the active region, thus greatly confines the electrons over there and tremendously decreases the electron leakage into the p-region. Moreover, such specially designed QBs reduce the quantum-confined Stark effect in the active region, thereby improves the electron and hole wavefunctions overlap. As a result, both the internal quantum efficiency and output power of the GSQB structure are ~2.13 times higher than the conventional structure at 60 mA. Importantly, our proposed structure exhibits only ~20.68% efficiency droop during 0–60 mA injection current, which is significantly lower compared to the regular structure.
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spelling pubmed-80039682021-03-28 Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers Jain, Barsha Velpula, Ravi Teja Patel, Moulik Sadaf, Sharif Md. Nguyen, Hieu Pham Trung Micromachines (Basel) Article To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type Al(x)Ga((1−x))N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, holes are depleted in the EBL due to the formation of positive sheet polarization charges at the heterointerface of the last quantum barrier (QB)/EBL. Subsequently, the hole injection efficiency of the LED is severely limited. In this regard, we propose an EBL-free AlGaN deep UV LED structure using graded staircase quantum barriers (GSQBs) instead of conventional QBs without affecting the hole injection efficiency. The reported structure exhibits significantly reduced thermal velocity and mean free path of electrons in the active region, thus greatly confines the electrons over there and tremendously decreases the electron leakage into the p-region. Moreover, such specially designed QBs reduce the quantum-confined Stark effect in the active region, thereby improves the electron and hole wavefunctions overlap. As a result, both the internal quantum efficiency and output power of the GSQB structure are ~2.13 times higher than the conventional structure at 60 mA. Importantly, our proposed structure exhibits only ~20.68% efficiency droop during 0–60 mA injection current, which is significantly lower compared to the regular structure. MDPI 2021-03-21 /pmc/articles/PMC8003968/ /pubmed/33801072 http://dx.doi.org/10.3390/mi12030334 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) ).
spellingShingle Article
Jain, Barsha
Velpula, Ravi Teja
Patel, Moulik
Sadaf, Sharif Md.
Nguyen, Hieu Pham Trung
Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
title Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
title_full Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
title_fullStr Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
title_full_unstemmed Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
title_short Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers
title_sort improved performance of electron blocking layer free algan deep ultraviolet light-emitting diodes using graded staircase barriers
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003968/
https://www.ncbi.nlm.nih.gov/pubmed/33801072
http://dx.doi.org/10.3390/mi12030334
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