Investigation of interstitial hydrogen and related defects in ZnO

Koßmann, Jörg; Hättig, Christof

doi:10.1039/c2cp42928d

Cited by 25 publications

(15 citation statements)

References 53 publications

(96 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this study, we always include the OH ∥ which was confirmed by the previous experiments for N = 2 via analyzing infra-red absorption spectrum 22 23 24 . (The two configurations differ in energy only by ~0.1 eV, to be consistent with previous literature 25 ).…”

Section: Resultssupporting

confidence: 92%

Light-Induced Peroxide Formation in ZnO: Origin of Persistent Photoconductivity

Kang

Nahm

Han

2016

Sci Rep

View full text Add to dashboard Cite

The persistent photoconductivity (PPC) in ZnO has been a critical problem in opto-electrical devices employing ZnO such as ultraviolet sensors and thin film transistors for the transparent display. While the metastable state of oxygen vacancy (VO) is widely accepted as the microscopic origin of PPC, recent experiments on the influence of temperature and oxygen environments are at variance with the VO model. In this study, using the density-functional theory calculations, we propose a novel mechanism of PPC that involves the hydrogen-zinc vacancy defect complex (2H-VZn). We show that a substantial amount of 2H-VZn can exist during the growth process due to its low formation energy. The light absorption of 2H-VZn leads to the metastable state that is characterized by the formation of (peroxide) around the defect, leaving the free carriers in the conduction band. Furthermore, we estimate the lifetime of photo-electrons to be ~20 secs, which is similar to the experimental observation. Our model also explains the experimental results showing that PPC is enhanced (suppressed) in oxygen-rich (low-temperature) conditions. By revealing a convincing origin of PPC in ZnO, we expect that the present work will pave the way for optimizing optoelectronic properties of ZnO.

show abstract

Section: Resultssupporting

confidence: 92%

Light-Induced Peroxide Formation in ZnO: Origin of Persistent Photoconductivity

Kang

Nahm

Han

2016

Sci Rep

View full text Add to dashboard Cite

show abstract

“…10 show the anticorrelation behavior between H O and H 2 signals which rules out the oxygen vacancy as a trapping center for the molecule. This conclusion is supported by recent calculations of the LVM frequency of H 2 located at the V O to be 3991 cm −1 , which significantly deviates from the experimentally observed value [63]. In addition, the negatively charged interstitial hydrogen H − i is unstable for all Fermi levels in the band gap preventing the formation mechanism proposed by Du and Biswas [18,22,64].…”

Section: F Position In the Latticesupporting

confidence: 50%

Towards understanding the hydrogen molecule in ZnO

2014

View full text Add to dashboard Cite

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.

show abstract

“…Van de Walle exploded the researches related to hydrogen in ZnO [7] after the conclusion that hydrogen behaves as a shallow donor in ZnO thin films. After that, there have been numerous experimental as well as theoretical reports which proved and expanded the role of hydrogen in ZnO [8][9][10][11][12][13][14][15][16]. Hydrogen could be unor intentionally incorporated into ZnO films during depositing and it could locate at H BC or H AB as the configuration proposed by Van de Walle [7].…”

Section: Introductionmentioning

confidence: 98%

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

Hoang

Phạm

Nguyen

et al. 2021

Journal of Nanomaterials

View full text Add to dashboard Cite

In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the c -axis (AB┴), into bond center sites paralleled to the c -axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature.

show abstract

Investigation of interstitial hydrogen and related defects in ZnO

Cited by 25 publications

References 53 publications

Light-Induced Peroxide Formation in ZnO: Origin of Persistent Photoconductivity

Light-Induced Peroxide Formation in ZnO: Origin of Persistent Photoconductivity

Towards understanding the hydrogen molecule in ZnO

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

Contact Info

Product

Resources

About