Strong visible and near infrared luminescence in undoped YAG single crystals

Varney, C. R.; Reda, Sherif M.; Mackay, David T.; Rowe, Michael C.; Selim, F. A.

doi:10.1063/1.3671646

Cited by 40 publications

(27 citation statements)

References 17 publications

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“…The UV emission in undoped YAG originates from self-trap excitons associated with Al vacancies, while the visible emission is due to impurities (Ce, Cr, and Fe impurities.). 35,36 Glow discharge mass spectroscopy (GDMS) confirmed the presence of these impurities in the measured samples. While O-grown samples exhibit very strong emission (Fig.…”

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confidence: 57%

Hydrogen in insulating oxide Y₃Al₅O₁₂ strongly narrows the band gap

2014

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We report an unusual band gap narrowing in Y 3 Al 5 O 12 (YAG) insulating oxide after growing YAG single crystals in hydrogen atmosphere. Theory confirms that hydrogen interstitials as well as oxygen vacancies strongly shift the absorption spectrum towards lower energies. Furthermore, hydrogen eliminated all deep and shallow traps in the YAG structure and dramatically modified the optical and scintillation properties of YAG single crystals. We conclude that hydrogen plays a significant role in insulating oxides similar to its role in semiconductors and it may be used to passivate defects and improve exciton dynamics in oxides for optical and scintillation applications. V C 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4903343]Hydrogen does not exist as a neutral impurity in semiconductors and insulators; it always gives up an electron becoming positively charged impurity or acquires an electron becoming negatively charged impurity. 1 This has profound effects on the incorporation of hydrogen in the structure and the electronic and structural properties of materials. 2,3 The importance and significance of hydrogen in materials have been revealed theoretically by Van de Walle, Zunger, their co-workers, and other groups [e.g., Refs. 1, 2, and 4-8]; and hydrogen in semiconductors has been the subject of intense investigation. 1-22 It behaves in semiconductors in two fashions. It typically acts as passivating agent reducing the electrical conductivity 3,10 and recently found that in some semiconductors, such as ZnO, SnO 2 , In 2 O 3 , and InN, hydrogen is source of doping. 2,11,12,[15][16][17]20,21 In fact, many research efforts have been carried out to control hydrogen in both amorphous and crystalline semiconductors. Meanwhile, no or little attention has been paid to the role of hydrogen in insulators. In this work, we show that incorporation of hydrogen in the Y 3 Al 5 O 12 , yttrium aluminum garnet (YAG) structure has led to significant band gap narrowing (BGN) in Y 3 Al 5 O 12 single crystals, an unusual surprising effect for hydrogen incorporation in oxides. This BGN has been confirmed by experimental and theoretical results. Furthermore, we show that hydrogen binds to native defects passivating their role as exciton traps which has remarkable impact on the optical and scintillation properties of YAG crystals. Like in semiconductors, hydrogen plays a significant role in insulating oxides and requires immediate attention, not only because hydrogen can be incorporated unintentionally as impurity into the materials and is impossible to avoid 2 but also it may provide a versatile tool to control traps and improve exciton dynamics in optical and scintillation materials. In scintillation materials, defects with deep level in the band gap may trap charge carriers and excitons preventing their transport to luminescence centers. This reduces the efficiency of luminescence and scintillation. On the other hand, defects with shallow level in the band gap trap and detrap charge carriers and excitons at room temperatu...

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confidence: 57%

Hydrogen in insulating oxide Y₃Al₅O₁₂ strongly narrows the band gap

2014

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“…Nevertheless, some individual kinds of iron-containing substances demonstrate the existence of the phenomenon of luminescence, particularly, in yttrium aluminum garnets where the emission with the wavelength at 800 nm due to transition in Fe 3+ in tetrahedral position was observed [20]. We can conclude from Fig.…”

Section: Discussionmentioning

confidence: 53%

Effects of Transition-Metal-Doping on the Radio-Luminescence Properties of Magnesium Aluminate Spinel Crystals

Gritsyna¹,

Kazarinov²

2018

RadJ

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Abstract. The use of the radio-luminescence (RL) method for radiation-induced processes in magnesium aluminates spinel crystals (MgO•nAl2O3) of different composition doped with transition metals (Mn, Cr, and Fe) was investigated. The RL spectra demonstrate bands related to the intrinsic defects, such as anti-site defects (263 nm) and F-type centers (~360 nm). Transition metal (TM) ions substituting the crystal-forming ions in the tetra-and octahedral sites show the emission due to electron transitions in doped ions, particularly, band at 520 nm identified with the transition in Mn 2+ in tetrahedral positions and the emission in the red spectral region (consisting of zerophonon line at 686.6 nm and phonon-assisted lines) related to the transition in Cr 3+ ions at the octahedral position. Based on the data on the quenching UV luminescence in stoichiometric crystals doped with TM, we suggest the partial ordering of this type of crystals. The enhancement of Cr 3+ luminescence in stoichiometric spinel crystals doped with manganese and iron supports this suggestion on the ordering of the spinel crystals by doping with some TM's. The existence of a large number of non-stoichiometric cationic vacancies in non-stoichiometric spinel crystals prevents the formation of an ordered structure.

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“…This sample will be also used later for TL glow curves presented in Figure 12. Some qualitative information can be gained from this figure in conjunction with prior knowledge about the sample, such as ascribing the peak at 256 nm to Fe impurities [77,78]. These plots give no information about the depth of these traps other than the fact that heating to 400°C seemed to clear them up which implies that they are deep centers.…”

Section: Tl Applied To Dielectricsmentioning

confidence: 99%

Trap Level Measurements in Wide Band Gap Materials by Thermoluminescence

Saadatkia¹,

Varney²,

Selim³

2016

Luminescence - An Outlook on the Phenomena and Their Applications

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The electrical and optical properties of wide band gap materials are greatly affected by the presence of defects in the band gap. Identification and characterization of these defects that act as electron and hole traps are essential to understand charge carrier and exciton dynamics and ultimately control the electrical and optical properties of dielectrics and semiconductors. In this chapter, we will demonstrate how thermoluminescence (TL) spectroscopy can be used to characterize traps and measure their energy levels in the band gap. An advanced wavelength-based TL spectrometer will be presented, and its applications for the evaluation of trap levels and the characterization of donors and acceptors in semiconductors and dielectrics will be discussed.

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Strong visible and near infrared luminescence in undoped YAG single crystals

Cited by 40 publications

References 17 publications

Hydrogen in insulating oxide Y₃Al₅O₁₂ strongly narrows the band gap

Hydrogen in insulating oxide Y₃Al₅O₁₂ strongly narrows the band gap

Effects of Transition-Metal-Doping on the Radio-Luminescence Properties of Magnesium Aluminate Spinel Crystals

Trap Level Measurements in Wide Band Gap Materials by Thermoluminescence

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Strong visible and near infrared luminescence in undoped YAG single crystals

Cited by 40 publications

References 17 publications

Hydrogen in insulating oxide Y3Al5O12 strongly narrows the band gap

Hydrogen in insulating oxide Y3Al5O12 strongly narrows the band gap

Effects of Transition-Metal-Doping on the Radio-Luminescence Properties of Magnesium Aluminate Spinel Crystals

Trap Level Measurements in Wide Band Gap Materials by Thermoluminescence

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Hydrogen in insulating oxide Y₃Al₅O₁₂ strongly narrows the band gap

Hydrogen in insulating oxide Y₃Al₅O₁₂ strongly narrows the band gap