Infrared absorption of hydrogen-related defects in ammonothermal GaN

Suihkonen, Sami; Pimputkar, Siddha; Speck, James S.; Nakamura, Shuji

doi:10.1063/1.4952388

Cited by 33 publications

(62 citation statements)

References 25 publications

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“…[43,44,79] The observed vacancy concentration is several orders of magnitude higher than what has been reported for HVPE grown material [78,80] and is expected to have a significant effect on the material properties. In GaN, gallium vacancies (V Ga ) and vacancy complexes form deep levels in the band-gap, [44,81,82] cause non-radiative recombination, [83] contribute to sub-bandgap optical absorption, [42] compensate n-type doping, [40] and have been associated with device degradation.…”

Section: Gallium Vacancies and Vacancy Clustersmentioning

confidence: 60%

“…[26,[34][35][36] Ammonothermal GaN substrates have been used in homoepitaxy [35,37,38] and as substrates for InGaN LDs. [39] Although the crystalline quality of ammonothermal GaN is very high, recent studies have shown that the high concentration of impurities [22,40,41] and native point defects [42][43][44] in the as-grown material have a significant effect on the material properties. The most dominant impurities, oxygen and transition metals, cause absorption in the visible region [23,42] and their non-uniform incorporation in the growing crystal can cause build-up of strain.…”

Section: Progress Reportmentioning

confidence: 99%

“…[31,40] optical absorption [42] and compensation doping. [43] Additionally, the formation of helical dislocations during heat treatment and epitaxy process has very recently been reported and associated with interaction of dislocations and point defects. [45] Here, we summarize recent progress in ammonothermal growth of GaN and consider the effects as-grown defects and dislocations have on the material properties.…”

Section: Progress Reportmentioning

confidence: 99%

“…Reported impurities result from bulk GaN crystals grown in a) basic ammonothermal chemistries in a NiCr superalloy autoclaves without a liner (NiCr), within a silver capsule (Ag), within a molybdenum capsule (Mo) and b) acidic ammonothermal chemistries in a lined Ni-based alloy autoclave (lined) or a TZM autoclave (TZM). [22,26,32,43,58,59,79,[126][127][128] (7 of 18) 1600496…”

Section: Progress Reportmentioning

confidence: 99%

“…[66,78,80] V Ga and their complexes can be detected by positron annihilation spectroscopy [88] and optical absorption measurements in the mid-infrared wavelength range. [43,44,89] …”

Section: Gallium Vacancies and Vacancy Clustersmentioning

confidence: 99%

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Defects in Single Crystalline Ammonothermal Gallium Nitride

Suihkonen

Pimputkar

Sintonen

et al. 2017

Adv Elect Materials

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Native bulk gallium nitride (GaN) has emerged as an alternative for sapphire and silicon as a substrate material for III‐N devices. While quasi‐bulk GaN substrates are currently commercially available, single crystal GaN substrates are considered essential for future high performance light emitters and power devices. The ammonothermal method is currently considered one of the most feasible methods to grow large truly bulk crystals of GaN at low cost and high structural quality. High crystalline quality GaN substrates sliced from ammonothermally grown crystals have been demonstrated and utilized in homoepitaxy for III‐N devices. However, despite the high crystalline quality the properties of as‐grown ammonothermal GaN crystals and substrates are affected by the presence of impurities and other defects that hinder their use for device applications. Here, the main developments of ammonothermal growth of GaN and the effects of impurities, native point defects, and dislocations on the material properties are summarized. Additionally, measurement techniques that enable the evaluation of point defect concentration and low dislocation density distribution over a large area on bulk GaN substrates are reviewed.

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Section: Gallium Vacancies and Vacancy Clustersmentioning

confidence: 60%

Section: Progress Reportmentioning

confidence: 99%

Section: Progress Reportmentioning

confidence: 99%

Section: Progress Reportmentioning

confidence: 99%

“…[66,78,80] V Ga and their complexes can be detected by positron annihilation spectroscopy [88] and optical absorption measurements in the mid-infrared wavelength range. [43,44,89] …”

Section: Gallium Vacancies and Vacancy Clustersmentioning

confidence: 99%

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Defects in Single Crystalline Ammonothermal Gallium Nitride

Suihkonen

Pimputkar

Sintonen

et al. 2017

Adv Elect Materials

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Photoluminescence from Vacancy‐Containing Defects in GaN

Reshchikov

2022

Physica Status Solidi (a)

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Optical studies of point defects in crystals began in the 1920s by Robert Pohl and his research group at the University of Göttingen. [1] For many years, the so-called color centers in alkali halides were the focus of these studies, and the primary defect of interest was F-center. [2][3][4][5] The F-center (named after the German word "Farbe" for color) is an anion vacancy; an example is V Cl in NaCl. The name "color centers," first used in 1930, is applied to atomic-size imperfections of a crystal lattice that cause Gaussian-like absorption bands in alkali halides. [1] The family of color centers quickly increased: the U, V, F', M, R, H, V k , F 2 , F 3 , … centers, which were thought to be primarily intrinsic (native) defects and their complexes. [1] (Typical terminology can be found in Refs. [3,6,7]). Theorists predicted that when light is absorbed in the characteristic absorption band (e.g., at 2.77 eV for NaCl), luminescence may occur at lower photon energy. [8,9] In particular, Pekar [9] calculated for the F-center in NaCl that a luminescence band with a maximum at 0.99 eV should be observed at temperatures below 100 K. It took three decades after the beginning of optical studies to discover photoluminescence (PL) from these defects. First, Ghormley and Levy [10] have found a PL band that could be due to the F-center in KCl, while Klick [11] could not confirm it. Later, careful experiments of Botden et al. [12] unambiguously identified F-centers in KCl, RbCl, KBr, and KI. The absorption and emission spectra of color centers represent Gaussian-like bands, the shape and position of which can be explained with the configuration-coordinate (cc) model.At about the same time, intensive studies were conducted on luminescence from semiconductor phosphors, such as ZnS, which had applications in television tubes, fluorescent lamps, and X-Ray screens. Metal impurities (activators) were used to activate PL bands. However, sometimes, bright PL bands appeared without activation. These "self-activated" PL bands in ZnS were attributed to the zinc vacancy (V Zn ) associated with shallow donors (group-III impurities in the nearest Zn site or group-VII impurities in the S site). [13] Experiments with polarized PL confirmed the predicted symmetry of the defect complexes. [14] Later, very similar complexes were found in n-type GaAs, where strong self-activated luminescence with a maximum at 1.2 eV has been attributed to the gallium vacancy-donor complexes, such as V Ga Te As and V Ga Sn Ga . [15][16][17] PL studies using polarized excitation and uniaxial pressure revealed that the Jahn-Teller distortions lower the symmetry of these defects. [18] Similarly, complexes involving the arsenic vacancy and shallow acceptors (V As Cd Ga and V As Zn Ga ) were proposed to be the origin of the 1.37 eV band in p-type GaAs. [19] GaN, being the third-generation semiconductor material (wide-bandgap semiconductors), has gained unprecedented attention in the past three decades due to its applications in light-emitting and high-power devices. Un...

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On the Origin of the Yellow Luminescence Band in GaN

Reshchikov

2022

Physica Status Solidi (b)

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The yellow luminescence (YL) band with a maximum at 2.2 eV is the dominant defect‐related luminescence in unintentionally doped GaN. The discovery of the mechanism responsible for this luminescence band and related defects in GaN took many years. Eventually, a consensus has been reached that the CN acceptor is the source of the YL band (the YL1 band) in GaN samples grown by several techniques. Previously suggested candidates, such as VGa, VGaON, CNON, and CNSiGa, should be discarded. At the same time, other defects (such as the VN, BeGa, and CaGa) may cause luminescence bands with positions and shapes not much different from the YL1 band. In GaN containing high concentrations of gallium vacancies, oxygen, and hydrogen, complexes containing these species may also contribute in the red–yellow part of the photoluminescence spectrum. The main controversies related to the YL band are resolved.

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Infrared absorption of hydrogen-related defects in ammonothermal GaN

Cited by 33 publications

References 25 publications

Defects in Single Crystalline Ammonothermal Gallium Nitride

Defects in Single Crystalline Ammonothermal Gallium Nitride

Photoluminescence from Vacancy‐Containing Defects in GaN

On the Origin of the Yellow Luminescence Band in GaN

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