Hydrogen-related complexes in Li-diffused ZnO single crystals

Corolewski, Caleb; Parmar, Narendra S.; Lynn, Kelvin G.; McCluskey, M. D.

doi:10.1063/1.4959106

Cited by 13 publications

(5 citation statements)

References 40 publications

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“…It has been interesting to note that pristine, "undoped" ZnO as often reported in the literature in fact has a finite amount of H in it-either by accident (synthesis through wet-chemical routes or ALD, MOCVD etc) or intentional. 1 The other major defect in ZnO are oxygen vacancies and to a smaller possibility, Zn interstitials. All three of these defect types, viz., hydrogen (interstitial H = H i + é and substitutional), oxygen vacancies (V O + 2é) and Zn interstitials (Zn i + 2é) generally act as background donors, leading to n-type character in "undoped" ZnO.…”

mentioning

confidence: 99%

A Structural and ac Conductivity Study on Li Doped ZnO

Karthika¹,

Varrier²,

Kumar³

2021

ECS J. Solid State Sci. Technol.

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In the present work, the incorporation of Li in a wurtzite ZnO host synthesized through a chemical route has been studied experimentally. Starting with Yoshio's model, [K. Yoshio, A. Onodera, H. Satoh, N. Sakagami and H. Yamashita, Ferroelectrics, 264, 133 (2001)] structural refinement of the powder diffraction data suggests that Li has a mixed occupancy at both the substitutional 2b (≈1.2%) and interstitial 2a (≈12.6%) Wykoff sites. In comparison with a pure ZnO sample, the net result appears to be an overall expansion of the unit cell by ∼0.07% along both a and c -axes. Temperature dependant ac conductivity measurements carried out using a two electrode assembly and the influence of superimposed dc bias suggest that the conduction may be governed by both the presence of interstitial Li and polar defect complexes also. The grains seem to respond more to an applied dc bias (an order of magnitude change in resistivity) than grain boundaries.

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confidence: 99%

A Structural and ac Conductivity Study on Li Doped ZnO

Karthika¹,

Varrier²,

Kumar³

2021

ECS J. Solid State Sci. Technol.

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“…It was observed that Li generates additional holes at the Zn substitution site, while it generates additional electrons at the interstitial site. It can be hypothesized that Li serves as a defect mediator in ZnO NPs [32,33].…”

Section: Field Emission Scanning Electron Microscopy (Fesem)mentioning

confidence: 99%

Effect of Zinc Oxide on the Efficiency Enhancement of Al/Li2O/PSi/Si/Al solar cell

Al-Hussan

Bakr

Ahmed

2021

Preprint

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In this paper, electrochemical etching of the p-type silicon wafer is used to prepare p-type porous silicon with current density of 10 mA.cm− 2 for 10 minutes. Field Emission Scanning Electron Microscopy (FESEM) has been used to study porous silicon layer surface morphology. Zinc oxide and lithium oxide nanoparticles are prepared separately by chemical precipitation method and simple precipitation method, respectively and deposited on glass substrates by drop casting method. Moreover,, the structural properties of the films were analyzed by using XRD and SEM. The XRD results showed that the ZnO and Li2O films are polycrystalline with hexagonal wurtzite structure and cubic structure, and preferred orientation along (101) and (003) planes, respectively. Using Scherrer's formula, the crystallite size was measured and it was found that ZnO and Li2O thin films have a crystallite size of 22.04 and 45.6 nm respectively. Surface topography of the prepared thin films is studied by using Scanning Electron Microscopy (SEM). Later, certain proportions of both materials were mixed and deposited on porous silicon using drop casting method at thickness of 1.4 µm. After that, the characteristics of the solar cell were investigated. Mixing zinc oxide nanoparticles in particular proportions with lithium oxide played a major role in increasing the solar cell's performance. The highest prepared film efficiency was obtained at mixing ratio (0.5: 0.5) for (ZnO: Li2O) and its value was (11.09 %).

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“…Zinc oxide is an n‐type semiconductor with a wide bandgap of 3.3 eV and high exciton binding energies of around 60 meV at room temperature 1,2 . The native electronic conduction in ZnO is ascribed to point defects such as oxygen vacancies, zinc interstitials, and finite amounts of hydrogen—either by accident or intentional 3,4 . The oxygen vacancies in ZnO ( V O •• ) have relatively low formation energies (≈3.72 eV) 5 ; therefore, they are prevalent point defects, but sluggish ion conductors owing to their relatively large migration energy (2.4 eV) 5 .…”

Section: Introductionmentioning

confidence: 99%

“…1,2 The native electronic conduction in ZnO is ascribed to point defects such as oxygen vacancies, zinc interstitials, and finite amounts of hydrogen-either by accident or intentional. 3,4 The oxygen vacancies in ZnO (V O •• ) have relatively low formation energies (≈3.72 eV) 5 ; therefore, they are prevalent point defects, but sluggish ion conductors owing to their relatively large migration energy (2.4 eV). 5 On the other hand, zinc interstitials (Zn i •• ) have high formation energies (≈6.35 eV) but are easily annihilated from ZnO even at room temperature because of low migration energies (0.57 eV).…”

Section: Introductionmentioning

confidence: 99%

On the flash sintering behavior of Li:ZnO—Evidence of electrode asymmetry driven by electrochemical reactions

Chi

2023

J Am Ceram Soc.

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The synthesis, subsequent flash sintering (FS) characteristics and microstructures of pure and Li‐incorporated ZnO powders are reported. At low concentrations, Li is a substitutional occupant in ZnO but becomes an amphoteric dopant (substitutional and interstitial occupant) at higher concentrations inferred from a contraction reversal of the unit cell volume. Increasing Li reduces the average flash temperature of ZnO modestly by 15°C, and a doubling of the linear shrinkage. A discernible color smear (yellow–white–dark) stretching from the anode to cathode imputable to strong electromigration is also observed. Microanalyses of the electrode regions establish clear evidence of electrochemical (EC) lithiation into ZnO and the formation of Li–Zn compounds not observed in conventional sintering (CS). Interestingly, in contrast to CS, the addition of Li enhances coarsening during FS, suggestive of a dissolution–reprecipitation process concurrent with the EC lithiation process. Evidence for considerable (local) yet tangible temperature, chemical and microstructural asymmetry among electrodes driven by EC reactions is presented. Probable mechanisms, leading to these observations, are discussed.

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Hydrogen-related complexes in Li-diffused ZnO single crystals

Cited by 13 publications

References 40 publications

A Structural and ac Conductivity Study on Li Doped ZnO

A Structural and ac Conductivity Study on Li Doped ZnO

Effect of Zinc Oxide on the Efficiency Enhancement of Al/Li2O/PSi/Si/Al solar cell

On the flash sintering behavior of Li:ZnO—Evidence of electrode asymmetry driven by electrochemical reactions

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