Impacts of Si-doping on vacancy complex formation and their influences on deep ultraviolet luminescence dynamics in Al<sub>x</sub>Ga<sub>1−x</sub>N films and multiple quantum wells grown by metalorganic vapor phase epitaxy

Chichibu, S. F.; Miyake, Hideto; Uedono, Akira

doi:10.35848/1347-4065/ac46b1

Cited by 7 publications

(1 citation statement)

References 138 publications

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“…Positron annihilation spectroscopy has been extensively employed to characterize vacancy defects in nitride semiconductors GaN, AlN and InN as well as their alloys in the past three decades. [2][3][4][5][6][7][8][9][10] The main defects found are cation (group III) vacancies and their complexes with residual impurities such as O and H, and with N vacancies. It should be noted that the N vacancies are generally not detectable with positrons due to their small size and often positive charge (they are positively charged throughout most of the bandgap in all nitrides).…”

Section: Introductionmentioning

confidence: 99%

Defects in nitride semiconductors as seen by positrons

Tuomisto

2024

Gallium Nitride Materials and Devices XIX

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Positron annihilation spectroscopy is a powerful set of methods for the detection, identification and quantification of vacancy-type defects in semiconductors. In the past decades, it has been used to reveal the relationship between the (opto-)electronic properties and specific defects in a wide variety of elemental and compound semiconductors, including nitrides. In binary compounds, the selective sensitivity of the technique is rather strongly limited to cation vacancies that possess significant open volume and suitable charge: negative of neutral. The focus of this paper is in the recent advances in combining state-of-the-art positron annihilation experiments and ab initio computational approaches in identifying and quantifying defects in AlGaN alloys and GaN/AlGaN device structures.

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Section: Introductionmentioning

confidence: 99%

Defects in nitride semiconductors as seen by positrons

Tuomisto

2024

Gallium Nitride Materials and Devices XIX

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Room-temperature nonradiative recombination lifetimes in c-plane Al1−xInxN epilayers nearly and modestly lattice-matched to GaN (0.11 ≤ x ≤ 0.21)

Shima

Yamanaka

et al. 2022

Journal of Applied Physics

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Lattice-matched Al1− xIn xN / GaN heterostructures with InN mole fraction ( x) of 0.18 have attracted considerable interest for use in GaN-based optoelectronic devices. Because the light emission efficiency ([Formula: see text]) of Al1− xIn xN alloys is far less than that of In xGa1− xN, understanding its causes is essential. For this purpose, room-temperature photoluminescence lifetime ([Formula: see text]), which almost represents the nonradiative recombination lifetime that limits the internal quantum efficiency in low [Formula: see text] semiconductors, of c-plane Al1− xIn xN epilayers nearly and modestly lattice-matched to GaN ([Formula: see text]) was examined. For the epilayers grown on low threading dislocation density (TDD) GaN substrates ([Formula: see text]), [Formula: see text] principally decreased with increasing x, indicating a progressive increase in the concentration of nonradiative recombination centers (NRCs), [Formula: see text]. One of the probable causes is the growth temperature ([Formula: see text]) reduction that is indispensable to incorporate more In, because in insufficient [Formula: see text] regime higher [Formula: see text] is preferred for enhancing the surface migration of adatoms to decrease the concentrations of vacancies that compose NRCs. The Al1− xIn xN epilayers of the same x but grown on high TDD ([Formula: see text]) GaN-on-sapphire templates exhibited shorter [Formula: see text]. Because the diffusion length of minority carriers was nearly zero in the Al1− xIn xN epilayers, the shorter [Formula: see text] indicates higher bulk [Formula: see text] in high TDD epilayers. The Al1− xIn xN epilayers of considerably rough surface morphologies exhibited spatially inhomogeneous [Formula: see text], implying that excited carriers recombined everywhere at InN-rich to InN-poor portions, where [Formula: see text] were likely lower to higher, respectively, than the average due to the deviations in the surface stoichiometry at various non- c-plane surfaces at a given [Formula: see text].

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Operation-induced degradation mechanisms of 275-nm-band AlGaN-based deep-ultraviolet light-emitting diodes fabricated on a sapphire substrate

Chichibu

Nagata

Oya

et al. 2023

Applied Physics Letters

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Degradation mechanisms of 275-nm-band AlxGa1-xN multiple quantum well deep-ultraviolet light-emitting diodes fabricated on a (0001) sapphire substrate were investigated under hard operation conditions with the current of 350 mA and the junction temperature of 105 °C. The optical output power (Po) initially decreased by about 20% within the operating time less than 102 h and then gradually decreased to about 60% by 484 h. For elucidating the causes for the initial and subsequent degradations, complementary electrical, time-resolved photoluminescence (TRPL), and impurity characterizations were carried out making a connection with the energy band profiles. Because the degradation of the wells was less significant than the Po reduction, the initial degradation is attributed essentially to the decrease in carrier injection efficiency (ηinjection), not in internal quantum efficiency of the wells, most likely due to depassivation of initially H-passivated preexisting nonradiative recombination centers (NRCs) in a Mg-doped p-type Al0.85Ga0.15N electron blocking layer. The principal cause for the subsequent Po reduction until 484 h is attributed to further decrease in ηinjection due to the appearance of certain current bypasses in addition to continuous depassivation of the NRCs in p-type AlxGa1-xN layers. According to our database on the species of vacancy-type defects acting as NRCs in GaN and AlN, which have been identified using the combination of positron annihilation and TRPL measurements, vacancy clusters comprised of a cation vacancy (VIII) and nitrogen vacancies (VN), such as VIIIVN2∼4, are the most suspicious origins of the NRCs in Mg-doped p-type AlxGa1-xN layers.

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Impacts of Si-doping on vacancy complex formation and their influences on deep ultraviolet luminescence dynamics in Al_xGa_1−xN films and multiple quantum wells grown by metalorganic vapor phase epitaxy

Cited by 7 publications

References 138 publications

Defects in nitride semiconductors as seen by positrons

Defects in nitride semiconductors as seen by positrons

Room-temperature nonradiative recombination lifetimes in c-plane Al1−xInxN epilayers nearly and modestly lattice-matched to GaN (0.11 ≤ x ≤ 0.21)

Operation-induced degradation mechanisms of 275-nm-band AlGaN-based deep-ultraviolet light-emitting diodes fabricated on a sapphire substrate

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Impacts of Si-doping on vacancy complex formation and their influences on deep ultraviolet luminescence dynamics in AlxGa1−xN films and multiple quantum wells grown by metalorganic vapor phase epitaxy

Cited by 7 publications

References 138 publications

Defects in nitride semiconductors as seen by positrons

Defects in nitride semiconductors as seen by positrons

Room-temperature nonradiative recombination lifetimes in c-plane Al1−xInxN epilayers nearly and modestly lattice-matched to GaN (0.11 ≤ x ≤ 0.21)

Operation-induced degradation mechanisms of 275-nm-band AlGaN-based deep-ultraviolet light-emitting diodes fabricated on a sapphire substrate

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Impacts of Si-doping on vacancy complex formation and their influences on deep ultraviolet luminescence dynamics in Al_xGa_1−xN films and multiple quantum wells grown by metalorganic vapor phase epitaxy