Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material

Le, Oanh Kieu Truong; Phạm, Anh Tuấn; Pham, Ngoc Kim; Pham, Trang Huyen Cao; Nguyen, Thu Hien; Hoang, Dung Van; Ta, Hanh Kieu Thi; Truong, Dai Cao; Lai, Hoa Thi; Ung, Thuy Dieu Thi; Trần, Vinh Cao; Phan, Thắng Bách

doi:10.1016/j.jmat.2020.12.020

Cited by 10 publications

(3 citation statements)

References 57 publications

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“…However, ITO is expensive due to the scarcity of indium. ZnO has emerged as an alternative material for ITO because it has many advantages, such as a wide band gap semiconductor (3.37 eV), a high exciton binding energy (60 meV), low toxicity, low cost, and high thermal stability 3 . However, due to a low carrier concentration, pure ZnO normally has weak electrical conductivity.…”

Section: Introductionmentioning

confidence: 99%

Relationship between electrical and optical characterization of Ga-doped ZnO thin films deposited by magnetron sputtering

2023

Sci. Tech. Dev. J.

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Introduction: Transparent conducting films have received much attention in energy conversion applications. To replace high-cost indium-tin-oxide (ITO), Ga-doped ZnO (GZO) film is considered due to its high conductivity, good transparency, low cost, and low toxicity. Methods: GZO and pure ZnO films were deposited on glass substrates by dc magnetron sputtering. The crystalline structure of the samples was verified by using X-ray diffraction. In particular, the relationship between the electrical and optical characterization of the GZO film was investigated through the plasma wavelength obtained from transmittance and reflectance spectra. Meanwhile, carrier transport was directly confirmed by Hall effect-based measurements. Results: The GZO film shows a hexagonal wurtzite structure, with successful incorporation of Ga into the ZnO lattice. Ga doping increases the carrier concentration, leading to a decrease in the resistivity of the film. This study also discusses the correlation of carrier transport obtained from Hall effect-based measurements and optical spectroscopies. Here, we extracted the optical carrier concentration and optical mobility from the plasma wavelength and compared them with the Hall data. Conclusion: The dependence of carrier transport on ionized impurity scattering can be pointed out. It proposes an effective way to qualitatively predict the electrical characteristics and transport properties of thin films via optical transmittance and reflectance analysis.

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Section: Introductionmentioning

confidence: 99%

Relationship between electrical and optical characterization of Ga-doped ZnO thin films deposited by magnetron sputtering

2023

Sci. Tech. Dev. J.

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“…19,23 Zn substitution with Ga and In, as well as second phases, was recently discovered to be the leading mechanisms for PF improvement at elevated temperatures. 27 Nevertheless, evidence for the origin of the peculiar behavior of S vs σ via second-phase precipitation has not been established so far.…”

Section: Introductionmentioning

confidence: 99%

“…In this sense, the method of chemical synthesis is somewhat problematic and time-consuming since it provides low yield and uncontrolled defect formation. In addition, there are a few studies demonstrating the effectiveness of second phases in the enhancement of TE performance of ZnO. , Zn substitution with Ga and In, as well as second phases, was recently discovered to be the leading mechanisms for PF improvement at elevated temperatures . Nevertheless, evidence for the origin of the peculiar behavior of S vs σ via second-phase precipitation has not been established so far.…”

Section: Introductionmentioning

confidence: 99%

Effects of Co-doping and Microstructure on Charge Carrier Energy Filtering in Thermoelectric Titanium-Doped Zinc Aluminum Oxide

Gayner

Natanzon

Amouyal

2022

ACS Appl. Mater. Interfaces

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ZnO is a promising thermoelectric (TE) material for high-temperature applications; however, its TE performance is limited by strong coupling between electrical and thermal transport. In this study, we synthesized Al and Ti co-doped ZnO by a solid-state reaction and air sintering at 1500 °C and analyzed the microstructure to establish its correlation with TE properties. The TE transport properties were measured between room temperature and 800 °C, and electronic properties were calculated from first principles calculations. Herein, we introduced second and third phases into a ZnO-based matrix to enhance its power factor (PF) by charge carrier energy filtering by applying co-doping with Al and Ti. Although multiphase materials usually do not exhibit high PF, in this study, it is observed that three-phase ZnO-based materials exhibit higher PF values compared to the two-phase materials. We observed unusual behavior, in which the Seebeck coefficient (S ) and electrical conductivity (σ) values increased simultaneously with temperature for Zn 1−x−y Al x Ti y O, originating from energy filtering of charge carriers due to both co-doping and the peculiar multiphase structure. High σ values were associated with the increase of electron concentration, while high S values were due to Fermi energy tuning and heavier effective masses initiated by Al and Ti co-doping. Besides increasing the PF, the multiphase structure played an essential role in reducing lattice thermal conductivity due to phonon scattering by the Umklapp, point defect, and second-phase mechanisms. Our approach yielded an increase of the TE figure of merit upon formation of a three-phase 2 wt % Ti-doped Zn 0.98 Al 0.02 O compound of ca. 10 times compared to the corresponding value attained for its two-phase ZnAl 0.02 O counterpart.

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Record‐High Thermoelectric Performance in Al‐Doped ZnO via Anderson Localization of Band Edge States

Serhiienko,

Novitskii,

Garmroudi

et al. 2024

Advanced Science

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Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco‐friendly constituting elements. Here, adopting a unique synthesis route via chemical co‐precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics ( 21.5 µW cm−1 K−2 and 0.5 at 1100 K in ) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi‐dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics.

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Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material

Cited by 10 publications

References 57 publications

Relationship between electrical and optical characterization of Ga-doped ZnO thin films deposited by magnetron sputtering

Relationship between electrical and optical characterization of Ga-doped ZnO thin films deposited by magnetron sputtering

Effects of Co-doping and Microstructure on Charge Carrier Energy Filtering in Thermoelectric Titanium-Doped Zinc Aluminum Oxide

Record‐High Thermoelectric Performance in Al‐Doped ZnO via Anderson Localization of Band Edge States

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