Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces

Gallium nitride is a wide-direct-bandgap semiconductor suitable for the creation of modern optoelectronic devices and radiation tolerant detectors. However, formation of dislocations is inevitable in MOCVD GaN materials. Dislocations serve as accumulators of point defects within space charge regions...

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Main Authors: Tomas Ceponis, Jevgenij Pavlov, Arunas Kadys, Augustas Vaitkevicius, Eugenijus Gaubas
Format: Article
Language:English
Published: MDPI AG 2023-04-01
Series:Materials
Subjects:
Online Access:https://www.mdpi.com/1996-1944/16/9/3424
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author Tomas Ceponis
Jevgenij Pavlov
Arunas Kadys
Augustas Vaitkevicius
Eugenijus Gaubas
author_facet Tomas Ceponis
Jevgenij Pavlov
Arunas Kadys
Augustas Vaitkevicius
Eugenijus Gaubas
author_sort Tomas Ceponis
collection DOAJ
description Gallium nitride is a wide-direct-bandgap semiconductor suitable for the creation of modern optoelectronic devices and radiation tolerant detectors. However, formation of dislocations is inevitable in MOCVD GaN materials. Dislocations serve as accumulators of point defects within space charge regions covering cores of dislocations. Space charge regions also may act as local volumes of enhanced non-radiative recombination, deteriorating the photoluminescence efficiency. Surface etching has appeared to be an efficient means to increase the photoluminescence yield from MOCVD GaN materials. This work aimed to improve the scintillation characteristics of MOCVD GaN by a wet etching method. An additional blue photo-luminescence (B-PL) band peaking at 2.7–2.9 eV and related to dislocations was discovered. This B-PL band intensity appeared to be dependent on wet etching exposure. The intensity of the B-PL was considerably enhanced when recorded at rather low temperatures. This finding resembles PL thermal quenching of B-PL centers. The mechanisms of scintillation intensity and spectrum variations were examined by coordinating the complementary photo-ionization and PL spectroscopy techniques. Analysis of dislocation etch pits was additionally performed by scanning techniques, such as confocal and atomic force microscopy. It was proved that this blue luminescence band, which peaked at 2.7–2.9 eV, is related to point defects those decorate dislocation cores. It was shown that the intensity of this blue PL band was increased due to enhancement of light extraction efficiency, dependent on the surface area of either single etch-pit or total etched crystal surface.
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spelling doaj.art-e81a6c45ce6342d7850f141abf4c5c872023-11-17T23:15:53ZengMDPI AGMaterials1996-19442023-04-01169342410.3390/ma16093424Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched SurfacesTomas Ceponis0Jevgenij Pavlov1Arunas Kadys2Augustas Vaitkevicius3Eugenijus Gaubas4Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio Ave. 3, LT-10257 Vilnius, LithuaniaInstitute of Photonics and Nanotechnology, Vilnius University, Sauletekio Ave. 3, LT-10257 Vilnius, LithuaniaInstitute of Photonics and Nanotechnology, Vilnius University, Sauletekio Ave. 3, LT-10257 Vilnius, LithuaniaInstitute of Photonics and Nanotechnology, Vilnius University, Sauletekio Ave. 3, LT-10257 Vilnius, LithuaniaInstitute of Photonics and Nanotechnology, Vilnius University, Sauletekio Ave. 3, LT-10257 Vilnius, LithuaniaGallium nitride is a wide-direct-bandgap semiconductor suitable for the creation of modern optoelectronic devices and radiation tolerant detectors. However, formation of dislocations is inevitable in MOCVD GaN materials. Dislocations serve as accumulators of point defects within space charge regions covering cores of dislocations. Space charge regions also may act as local volumes of enhanced non-radiative recombination, deteriorating the photoluminescence efficiency. Surface etching has appeared to be an efficient means to increase the photoluminescence yield from MOCVD GaN materials. This work aimed to improve the scintillation characteristics of MOCVD GaN by a wet etching method. An additional blue photo-luminescence (B-PL) band peaking at 2.7–2.9 eV and related to dislocations was discovered. This B-PL band intensity appeared to be dependent on wet etching exposure. The intensity of the B-PL was considerably enhanced when recorded at rather low temperatures. This finding resembles PL thermal quenching of B-PL centers. The mechanisms of scintillation intensity and spectrum variations were examined by coordinating the complementary photo-ionization and PL spectroscopy techniques. Analysis of dislocation etch pits was additionally performed by scanning techniques, such as confocal and atomic force microscopy. It was proved that this blue luminescence band, which peaked at 2.7–2.9 eV, is related to point defects those decorate dislocation cores. It was shown that the intensity of this blue PL band was increased due to enhancement of light extraction efficiency, dependent on the surface area of either single etch-pit or total etched crystal surface.https://www.mdpi.com/1996-1944/16/9/3424gallium nitridedislocationswet etchingphotoluminescencepulsed photo-ionization spectroscopy
spellingShingle Tomas Ceponis
Jevgenij Pavlov
Arunas Kadys
Augustas Vaitkevicius
Eugenijus Gaubas
Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces
Materials
gallium nitride
dislocations
wet etching
photoluminescence
pulsed photo-ionization spectroscopy
title Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces
title_full Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces
title_fullStr Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces
title_full_unstemmed Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces
title_short Luminescence Characteristics of the MOCVD GaN Structures with Chemically Etched Surfaces
title_sort luminescence characteristics of the mocvd gan structures with chemically etched surfaces
topic gallium nitride
dislocations
wet etching
photoluminescence
pulsed photo-ionization spectroscopy
url https://www.mdpi.com/1996-1944/16/9/3424
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AT jevgenijpavlov luminescencecharacteristicsofthemocvdganstructureswithchemicallyetchedsurfaces
AT arunaskadys luminescencecharacteristicsofthemocvdganstructureswithchemicallyetchedsurfaces
AT augustasvaitkevicius luminescencecharacteristicsofthemocvdganstructureswithchemicallyetchedsurfaces
AT eugenijusgaubas luminescencecharacteristicsofthemocvdganstructureswithchemicallyetchedsurfaces