Title Luminescence characteristics of the MOCVD GaN structures with chemically etched surfaces /
Authors Čeponis, Tomas ; Pavlov, Jevgenij ; Kadys, Arūnas ; Vaitkevičius, Augustas ; Gaubas, Eugenijus
DOI 10.3390/ma16093424
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Is Part of Materials.. Basel : MDPI. 2023, vol. 16, iss. 9, art. no. 3424, p. [1-14].. eISSN 1996-1944
Keywords [eng] dislocations ; gallium nitride ; photoluminescence ; pulsed photo-ionization spectroscopy ; wet etching
Abstract [eng] 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.
Published Basel : MDPI
Type Journal article
Language English
Publication date 2023
CC license CC license description