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Molecular Beam Epitaxial Growth and Characterization of Algan Epilayers for Vertical Deep Ultraviolet Leds on Silicon.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Molecular Beam Epitaxial Growth and Characterization of Algan Epilayers for Vertical Deep Ultraviolet Leds on Silicon./
Author:	Zhang, Qihua.
Description:	1 online resource (168 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-05, Section: B.
Contained By:	Dissertations Abstracts International85-05B.
Subject:	Silicon. -
Online resource:	click for full text (PQDT)
ISBN:	9798380705417

Molecular Beam Epitaxial Growth and Characterization of Algan Epilayers for Vertical Deep Ultraviolet Leds on Silicon.
Zhang, Qihua.

Molecular Beam Epitaxial Growth and Characterization of Algan Epilayers for Vertical Deep Ultraviolet Leds on Silicon. - 1 online resource (168 pages)

Source: Dissertations Abstracts International, Volume: 85-05, Section: B.

Thesis (Ph.D.)--McGill University (Canada), 2023.

Includes bibliographical references

Light emitting didoes (LEDs) through vertical current injection offer numerous advantages including excellent heat dissipation and size scalability. Yet it remains difficult to realize AlGaN deep ultraviolet (deep UV, wavelength shorter than 300 nm) LEDs through vertical injection. Silicon (Si) substrates, owing to their excellent conductivity, easy to removal by chemical wet etching, and mature manufacturing process, are a promising platform for developing vertical AlGaN deep UV LEDs. Nevertheless, obtaining high quality AlGaN epilayers on Si substrate has remained a challenge due to the large lattice and thermal mismatch between AlN and Si. In this thesis, we demonstrate a nanowire template assisted buffer layer technology on Si that enables high-quality AlGaN epilayers on Si, which further enables vertical AlGaN deep UV LEDs.We first perform the molecular beam epitaxial growth and characterization of AlN epilayers on Si substrates using the nanowire template. Highly smooth AlN epilayers with root-mean-square (rms) roughness of less than 0.4 nm are obtained. Our detailed comparison between the AlN epilayers grown on the nanowire template and the AlN epilayers directly on Si confirms that the use of the nanowire template can improve the crystalline quality and relax the tensile stress from Si. Using such AlN buffer layer, AlGaN epilayers with Al content varying from 35% to 70% are developed. The internal quantum efficiency (IQE) for such AlGaN epilayers are in the range of 30 - 40% under low excitations.With these material developments, vertically injected, surface emitting AlGaN deep UV LEDs down to 247 nm are demonstrated, by far the shortest wavelength for deep UV LEDs on Si with AlGaN epilayers. To further improve the device electrical performance, we have explored the polarization doped AlGaN epilayers on Si by grading the Al content along the growth direction. Vertical LEDs emitting around 278 nm are realized, and with using the polarization enhanced doping, the device series resistance is reduced by a factor of 5. This thesis work provides a viable path not only for vertical semiconductor deep UV LEDs, but also for low-cost ultrawide bandgap semiconductor template, potentially impact both photonics and electronic devices.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380705417Subjects--Topical Terms:

640033
Silicon.
Index Terms--Genre/Form:

554714
Electronic books.

Molecular Beam Epitaxial Growth and Characterization of Algan Epilayers for Vertical Deep Ultraviolet Leds on Silicon.
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500 $a Source: Dissertations Abstracts International, Volume: 85-05, Section: B.
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502 $a Thesis (Ph.D.)--McGill University (Canada), 2023.
504 $a Includes bibliographical references
520 $a Light emitting didoes (LEDs) through vertical current injection offer numerous advantages including excellent heat dissipation and size scalability. Yet it remains difficult to realize AlGaN deep ultraviolet (deep UV, wavelength shorter than 300 nm) LEDs through vertical injection. Silicon (Si) substrates, owing to their excellent conductivity, easy to removal by chemical wet etching, and mature manufacturing process, are a promising platform for developing vertical AlGaN deep UV LEDs. Nevertheless, obtaining high quality AlGaN epilayers on Si substrate has remained a challenge due to the large lattice and thermal mismatch between AlN and Si. In this thesis, we demonstrate a nanowire template assisted buffer layer technology on Si that enables high-quality AlGaN epilayers on Si, which further enables vertical AlGaN deep UV LEDs.We first perform the molecular beam epitaxial growth and characterization of AlN epilayers on Si substrates using the nanowire template. Highly smooth AlN epilayers with root-mean-square (rms) roughness of less than 0.4 nm are obtained. Our detailed comparison between the AlN epilayers grown on the nanowire template and the AlN epilayers directly on Si confirms that the use of the nanowire template can improve the crystalline quality and relax the tensile stress from Si. Using such AlN buffer layer, AlGaN epilayers with Al content varying from 35% to 70% are developed. The internal quantum efficiency (IQE) for such AlGaN epilayers are in the range of 30 - 40% under low excitations.With these material developments, vertically injected, surface emitting AlGaN deep UV LEDs down to 247 nm are demonstrated, by far the shortest wavelength for deep UV LEDs on Si with AlGaN epilayers. To further improve the device electrical performance, we have explored the polarization doped AlGaN epilayers on Si by grading the Al content along the growth direction. Vertical LEDs emitting around 278 nm are realized, and with using the polarization enhanced doping, the device series resistance is reduced by a factor of 5. This thesis work provides a viable path not only for vertical semiconductor deep UV LEDs, but also for low-cost ultrawide bandgap semiconductor template, potentially impact both photonics and electronic devices.
520 $a Les diodes electroluminescentes (DEL) par injection de courant verticale offrent de nombreux avantages, notamment une excellente dissipation de la chaleur et une evolutivite de la taille. Cependant, il est difficile de realiser des DELs d'AlGaN a ultraviolets profonds (UV profonds, longueur d'onde inferieure a 300 nm) par injection verticale. Les substrats en silicium (Si), en raison de leur excellente conductivite, de leur facilite d'elimination par gravure humide chimique et de leur processus de fabrication mature, constituent une plate-forme prometteuse pour le developpement de DELs d'AlGaN a UV profondes verticales. Neanmoins, l'obtention d'epicouches d'AlGaN de haute qualite sur un substrat de Si est restee un defi en raison du grand reseau et de l'inadequation thermique entre l'AlN et le Si. Dans cette these, nous demontrons une technologie de couche tampon assistee par modele de nanofils sur Si qui permet des epicouches d'AlGaN de haute qualite sur Si, ce qui permet en outre des DELs d'AlGaN a UV profondes verticales.Nous effectuons d'abord la croissance epitaxiale par faisceau moleculaire et la caracterisation des epicouches d'AlN sur des substrats de Si a l'aide de la matrice de nanofils. Des epicouches d'AlN tres lisses avec une rugosite quadratique moyenne (rms) inferieure a 0,4 nm sont obtenues. Notre comparaison detaillee entre les epicouches d'AlN developpees sur la matrice de nanofils et les epicouches d'AlN directement sur Si confirme que l'utilisation de la matrice de nanofils peut ameliorer la qualite cristalline et relacher la contrainte de traction de Si. En utilisant une telle couche tampon d'AlN, des epicouches d'AlGaN avec une teneur en Al entre 35% et 70% sont developpees. L'efficacite quantique interne (IQE) pour ces epicouches d'AlGaN est de l'ordre de 30% a 40% sous de faibles excitations.Avec ces developpements de materiaux, des DELs d'AlGaN a UV profondes a emission de surface injectees verticalement jusqu'a 247 nm sont demontrees, de loin la longueur d'onde la plus courte pour les DELs a UV profondes sur Si avec des epicouches d'AlGaN. Pour ameliorer encore les performances electriques du dispositif, nous avons explore les epicouches d'AlGaN dopees en polarisation sur Si en graduant la teneur en Al le long de la direction de croissance. Des DELs verticales emettant autour de 278 nm sont realisees, et avec l'utilisation du dopage ameliore par polarisation, la resistance en serie du dispositif est reduite d'un facteur 5. Ce travail de these fournit une voie viable non seulement pour les DELs a UV profondes a semi-conducteur verticales, mais aussi pour un modele de semi-conducteur a bande interdite ultra large moins couteux, impactant potentiellement a la fois la photonique et les appareils electroniques.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Silicon. $3 640033
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650 4 $a Nanowires. $3 568223
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650 4 $a Light emitting diodes. $3 639549
650 4 $a Aluminum. $3 1025495
650 4 $a Molecular beam epitaxy. $3 906406
650 4 $a Energy. $3 784773
650 4 $a Geometry. $3 579899
650 4 $a Scanning electron microscopy. $3 768680
650 4 $a Analytical chemistry. $3 1182118
650 4 $a Electrical engineering. $3 596380
650 4 $a Engineering. $3 561152
650 4 $a Nanotechnology. $3 557660
650 4 $a Optics. $3 595336
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