Restoring the Properties of Transparent Al-Doped ZnO Thin Film Electrodes Exposed to Ambient Air

Mickan, Martin; Stoffel, M.; Rinnert, H.; Helmersson, Ulf; Horwat, David

doi:10.1021/acs.jpcc.7b03020

Cited by 11 publications

(11 citation statements)

References 43 publications

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“…A decrease in Hall mobility was comparably exhibited by all samples (Figure and ), which indicated the diffusion of water molecule‐derived species or oxygen molecules to the AZO thin films, thus increasing electron scattering at grain boundaries as reported by Mickan et al Figure shows the evolution of carrier concentration and Hall mobility as a function of annealing temperature of each sample before and after the damp heat test compared to the recovered results. After the damp heat test, carrier concentration and Hall mobility decreased for all samples where the highest carrier concentration and Hall mobility were maintained in AZO samples annealed at 550 °C.…”

Section: Resultssupporting

confidence: 65%

“…A grain boundary reconstruction of AZO films was suggested by Hüpkes et al where grains grew together and closed grain boundaries partially on the cost of other areas due to annealing. Mickan et al reported that annealing in a nitrogen atmosphere at 180°C could restore the property of sputtered AZO thin films aged for 6 months in the ambient air, where out‐diffusion of water molecule was suggested as the reason for the restored property of the films. This evidence might suggest no physical damage during the degradation test of AZO films.…”

Section: Introductionmentioning

confidence: 99%

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Evolution and Recovery of Electrical Property of Reactive Sputtered Al‐Doped ZnO Transparent Electrode Exposed to Harsh Environment

Machda

Ogawa

Okumura

et al. 2019

Physica Status Solidi (a)

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Al-doped ZnO (AZO) thin film is extensively studied as a promising alternative for Sn-doped In 2 O 3 (ITO) transparent electrode from the viewpoint of safety, environment, and material costs. However, most of AZO thin films are reported to degrade when exposed to high humidity. To find a key factor of durability, the electrical properties of AZO thin films after harsh conditions are characterized in this study. AZO thin films are prepared on glass substrates by reactive radiofrequency magnetron sputtering, followed by annealing at 400-550 C in a hydrogen atmosphere. For harsh environment, a damp heat test is performed at 85 C and 85% relative humidity, where the changes in both the carrier concentration and mobility are examined. It is found that the carrier concentration exhibits similar decreasing tendencies to conductivity degradation as a function of annealing temperature. This means that higher temperature contributes to the stability of carrier concentration, i.e., conductivity. Re-annealing is also conducted for the AZO samples after the damp heat test, and the original conductivity is successfully recovered. This indicates that the degradation mechanism involves the chemical aspect rather than physical damage such as cracks, which cannot be recovered by annealing.

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Section: Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Evolution and Recovery of Electrical Property of Reactive Sputtered Al‐Doped ZnO Transparent Electrode Exposed to Harsh Environment

Machda

Ogawa

Okumura

et al. 2019

Physica Status Solidi (a)

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“…The band-to-band absorption in the In-doped ZnO has proved existence of energy transfer between ZnO and indium [22] by peaks marked as 378 nm (3.28 eV) [23]. The case of peaks at 400 (3.1 eV) [24] and 409 nm (3.03 eV) [25] maybe originates from zinc vacancies as well as transitions between conduction band and Zn vacancies as acceptor levels in this structure. Based on results, some weak intensity peaks are also observed at 444, 468, 481 and 491 nm in the measured spectra.…”

Section: Resultsmentioning

confidence: 75%

Surface, optical and electrochemical performance of indium-doped ZnO/WO3 nano-composite thin films

et al. 2020

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Great demand on replacing emission and pollution-free materials for energy storage by traditional fossil fuels has led to investigating of high-performance electrochromic materials. Nano-composite for electrochromic device may be a good choice. In this paper, stack-structured indium-doped ZnO/WO 3 nano-composite thin films were deposited on glass, indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO)-coated glass substrates, respectively. Surface, optical and electrochromic (EC) performance of the prepared nano-composite films has been investigated. Electrochromic impedance spectroscopy (EIS), cyclic voltammetry, repeating chronoamperometry (CA) and chronocoulometry (CC) measurements were taken. The Raman spectroscopy measurement shows that high-intensity peaks are related to ZnO wurtzite structure for all substrates. In the CA measurement, the rate of Li + transfer between surface and electrolyte was faster for films coated onto ITO substrate. In addition, the intercalation/deintercalation of Li + was obviously found faster for films onto ITO substrate due to roughness, structure differences than the other sample. As an advantage of our nano-composite material, the absence of current decay in the both coloration and bleaching stages has proved superiority and stability of films as well as indium contribution. The reversibility of stack-structured InZnO/WO 3 nanocomposite films was computed as 30 and 50% for the film with ITO and FTO substrates. The highest coloration efficiency value has calculated as 80 and 69 cm 2 /C for nano-composite thin films deposited onto FTO substrate @ 632 and 550 nm, respectively. Warburg impedance element values were determined from the equivalent circuit model. Also, calculated charges were determined for bleaching or coloring process for all films.

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“…It becomes weaker with increasing annealing temperature at 300-700 • C due to the removal of these impurities by annealing. It has been reported in the case of AZO films deposited by reactive HiPIMS stored in ambient air contain hydroxyl groups in the bulk of the film, and these groups are released after subsequent annealing in reducing atmosphere [36]. The film resistivity significantly decreases after this release.…”

Section: Resultsmentioning

confidence: 97%

Role of Ambient Hydrogen in HiPIMS-ITO Film during Annealing Process in a Large Temperature Range

et al. 2022

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Indium tin oxide (ITO) thin films were prepared by high power impulse magnetron sputtering (HiPIMS) and annealed in hydrogen-containing forming gas to reduce the film resistivity. The film resistivity reduces by nearly an order of magnitude from 5.6 × 10−3 Ω·cm for the as-deposited film to the lowest value of 6.7 × 10−4 Ω·cm after annealed at 700 °C for 40 min. The role of hydrogen (H) in changing the film properties was explored and discussed in a large temperature range (300–800 °C). When annealed at a low temperature of 300–500 °C, the incorporated H atoms occupied the oxygen sites (Ho), acting as shallow donors that contribute to the increase of carrier concentration, leading to the decrease of film resistivity. When annealed at an intermediate temperature of 500–700 °C, the Ho defects are thermally unstable and decay upon annealing, leading to the reduction of carrier concentration. However, the film resistivity keeps decreasing due to the increase in carrier mobility. Meanwhile, some locally distributed metallic clusters formed due to the reduction effect of H2. When annealed at a high temperature of 700–800 °C, the metal oxide film is severely reduced and transforms to gaseous metal hydride, leading to the dramatic reduction of film thickness and carrier mobility at 750 °C and vanish of the film at 800 °C.

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Restoring the Properties of Transparent Al-Doped ZnO Thin Film Electrodes Exposed to Ambient Air

Cited by 11 publications

References 43 publications

Evolution and Recovery of Electrical Property of Reactive Sputtered Al‐Doped ZnO Transparent Electrode Exposed to Harsh Environment

Evolution and Recovery of Electrical Property of Reactive Sputtered Al‐Doped ZnO Transparent Electrode Exposed to Harsh Environment

Surface, optical and electrochemical performance of indium-doped ZnO/WO3 nano-composite thin films

Role of Ambient Hydrogen in HiPIMS-ITO Film during Annealing Process in a Large Temperature Range

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