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 <i>p</i>-type Al<sub>x</sub>Ga<sub>(1−x)</sub>N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-03-01
|
| Series: | Micromachines |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-666X/12/3/334 |
| _version_ | 1827697148439822336 |
|---|---|
| author | Barsha Jain Ravi Teja Velpula Moulik Patel Sharif Md. Sadaf Hieu Pham Trung Nguyen |
| author_facet | Barsha Jain Ravi Teja Velpula Moulik Patel Sharif Md. Sadaf Hieu Pham Trung Nguyen |
| author_sort | Barsha Jain |
| collection | DOAJ |
| description | To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich <i>p</i>-type Al<sub>x</sub>Ga<sub>(1−x)</sub>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 <i>p</i>-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. |
| first_indexed | 2024-03-10T13:03:08Z |
| format | Article |
| id | doaj.art-a7107743a14f4a9bb284bee79805da87 |
| institution | Directory Open Access Journal |
| issn | 2072-666X |
| language | English |
| last_indexed | 2024-03-10T13:03:08Z |
| publishDate | 2021-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Micromachines |
| spelling | doaj.art-a7107743a14f4a9bb284bee79805da872023-11-21T11:24:15ZengMDPI AGMicromachines2072-666X2021-03-0112333410.3390/mi12030334Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase BarriersBarsha Jain0Ravi Teja Velpula1Moulik Patel2Sharif Md. Sadaf3Hieu Pham Trung Nguyen4Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USADepartment of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USADepartment of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USACentre Energie, Matériaux et TéléCommunications, Institut National de la Recherche Scientifique (INRS), 1650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, CanadaDepartment of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USATo prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich <i>p</i>-type Al<sub>x</sub>Ga<sub>(1−x)</sub>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 <i>p</i>-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.https://www.mdpi.com/2072-666X/12/3/334AlGaN light-emitting diodeselectron-blocking layerpositive sheet polarization chargesthermal velocitygraded staircase quantum barriers (GSQBs) |
| spellingShingle | Barsha Jain Ravi Teja Velpula Moulik Patel Sharif Md. Sadaf Hieu Pham Trung Nguyen Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers Micromachines AlGaN light-emitting diodes electron-blocking layer positive sheet polarization charges thermal velocity graded staircase quantum barriers (GSQBs) |
| 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 | AlGaN light-emitting diodes electron-blocking layer positive sheet polarization charges thermal velocity graded staircase quantum barriers (GSQBs) |
| url | https://www.mdpi.com/2072-666X/12/3/334 |
| work_keys_str_mv | AT barshajain improvedperformanceofelectronblockinglayerfreealgandeepultravioletlightemittingdiodesusinggradedstaircasebarriers AT ravitejavelpula improvedperformanceofelectronblockinglayerfreealgandeepultravioletlightemittingdiodesusinggradedstaircasebarriers AT moulikpatel improvedperformanceofelectronblockinglayerfreealgandeepultravioletlightemittingdiodesusinggradedstaircasebarriers AT sharifmdsadaf improvedperformanceofelectronblockinglayerfreealgandeepultravioletlightemittingdiodesusinggradedstaircasebarriers AT hieuphamtrungnguyen improvedperformanceofelectronblockinglayerfreealgandeepultravioletlightemittingdiodesusinggradedstaircasebarriers |