Charge states of a hydrogen defect with a local vibrational mode at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>3326</mml:mn><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>in ZnO

Herklotz, F.; Lavrov, E. V.; Kolkovsky, Vl.; Weber, Jens; Stavola, Michael

doi:10.1103/physrevb.82.115206

Cited by 27 publications

(13 citation statements)

References 45 publications

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“…A reappearance of the bond-centered hydrogen was reported previously for low temperature hydrogenated ZnO by Shi et al [32]. A similar behavior was observed after annealing ZnO samples at 400 • C for the zinc vacancy decorated with two hydrogen atoms and a hydrogen-related mode at 3326 cm −1 [7,33,34]. At the surface, however, interstitial hydrogen either outdiffuses or gets trapped by the subsurface oxygen vacancies thus accounting for the missing H BC in the Raman spectra [27].…”

Section: Isochronal Annealingsupporting

confidence: 80%

Towards understanding the hydrogen molecule in ZnO

2014

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The hydrogen molecule H 2 (or "hidden" hydrogen) in ZnO is studied by Raman scattering spectroscopy. It is shown that H 2 is practically a free rotator stable up to 700 • C, which is formed by two mobile interstitial hydrogen atoms. The concentration profile of the hydrogen molecule anticorrelates with hydrogen substituting for oxygen (H O ) created at the sample surface during the high temperature hydrogenation. The H 2 dissociation at elevated temperatures in the bulk regenerates interstitial (H BC ) hydrogen, whereas the formation of H O and hydrogen out-diffusion are dominant decay channels of the molecule near the surface. The latter mechanisms are responsible for the lower stability of H 2 in the subsurface region. An ortho-para conversion between the nuclear spin states 1 and 0 of the molecule at 79 K was found to occur within 7.5 h, whereas the back conversion at room temperature occurs faster than 0.5 h. A shift in frequency of the H 2 local vibrational mode with annealing time and temperature is associated with the thermal anneal of lattice imperfections. The coupling of transitions between rotational states of the molecule and lattice phonons influences the ro-vibrational properties. Interstitial lattice sites and/or larger vacancy clusters are preferred trapping centers for H 2 in ZnO.

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Section: Isochronal Annealingsupporting

confidence: 80%

Towards understanding the hydrogen molecule in ZnO

2014

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“…8(a)] for the temperatures above 300 • C. A similar behavior was observed after annealing ZnO at 400 • C for the zinc vacancy passivated with one or two hydrogen atoms [6,14,59,60]. At 650 • C, bond-centered hydrogen (deuterium) reaches its maximum concentration but after annealing at 800 • C the defect is finally gone.…”

Section: Annealing Properties Of H Bc and H Osupporting

confidence: 59%

“…The annealing temperature of H BC depends on the amount of other hydrogen trapping centers and in pure material is determined solely by the formation rate of hydrogen molecules [14,15]. For concentrations of bond-centered hydrogen at 10 17 cm −3 , the annealing temperature was reported to be around 200 • C [7,16,17].…”

Section: Introductionmentioning

confidence: 99%

Interplay between interstitial and substitutional hydrogen donors in ZnO

2014

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A Raman study on hydrogen donors in ZnO reveals the properties of bond-centered hydrogen (H BC ) and hydrogen trapped in the oxygen vacancy (H O ). The donors are identified by their electronic 1s → 2s(2p) transitions and their characteristic local vibrational modes. The H O donor was detected preferentially below the sample surface, where a high oxygen vacancy concentration is generated by thermal treatment of the samples. H BC and H O exhibit different thermal stabilities and their concentrations depend strongly on the sample history. Molecular hydrogen is an essential part of the interplay of the two hydrogen donors.

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“…21 In particular, recent IR absorption studies suggest that V Zn H acts as a deep acceptor in ZnO and gives rise to the 3326 and 3358 cm −1 local vibrational modes (LVMs) assigned to the negative and the neutral charge states of the defect, respectively. 22 The ground state of V Zn H 2 comprises two nonequivalent O-H bonds. 11 One of them is aligned 10 • off the c axis of the crystal (OH ) and gives rise to a LVM at 3312.2 cm −1 .…”

Section: Introductionmentioning

confidence: 99%

Metastable state of theVZnH2defect in ZnO

2011

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The Zn vacancy passivated by two hydrogen atoms in ZnO (V Zn H 2 ) was studied by IR absorption. In addition to the ground state of the defect comprising two inequivalent O-H bonds aligned parallel and perpendicular to the c axis of the crystal, there exists a metastable state of the defect (V Zn H * 2 ). V Zn H * 2 consists of two equivalent O-H bonds oriented perpendicular to the c axis. The metastable state reveals two local vibration modes at 3329.0 and 3348.4 cm −1 , which represent antisymmetric and symmetric combinations of the two separate O-H stretch modes, respectively. The energy difference between the ground and the metastable states of the complex was found to be 75 ± 9 meV. An activation energy of 0.96 ± 0.12 eV is needed to move the hydrogen atom from the c axis to the perpendicular position.

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Charge states of a hydrogen defect with a local vibrational mode at3326 cm−1in ZnO

Cited by 27 publications

References 45 publications

Towards understanding the hydrogen molecule in ZnO

Towards understanding the hydrogen molecule in ZnO

Interplay between interstitial and substitutional hydrogen donors in ZnO

Metastable state of theVZnH2defect in ZnO

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