Crystallization behavior of amorphous indium–gallium–zinc-oxide films and its effects on thin-film transistor performance

Suko, Ayaka; Jia, Junjun; Nakamura, Shin; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki; Shigesato, Yuzo

doi:10.7567/jjap.55.035504

Cited by 23 publications

(25 citation statements)

References 18 publications

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“…As expected, at a higher annealing temperature of 700 °C, the XRD spectrum shows a discernible (009) diffraction peak. This indicates that the IGZO layer has crystallized, which agrees with previous reports in the literature 34 . Next, the Ta layer is applied on top of the amorphous IGZO layer and annealed at temperatures ranging from 200 to 500 °C.…”

Section: Resultssupporting

confidence: 92%

The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer

Shin

Kim

et al. 2017

Sci Rep

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High-mobility indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are achieved through low-temperature crystallization enabled via a reaction with a transition metal catalytic layer. For conventional amorphous IGZO TFTs, the active layer crystallizes at thermal annealing temperatures of 600 °C or higher, which is not suitable for displays using a glass substrate. The crystallization temperature is reduced when in contact with a Ta layer, where partial crystallization at the IGZO back-channel occurs with annealing at 300 °C, while complete crystallization of the active layer occurs at 400 °C. The field-effect mobility is significantly boosted to 54.0 cm2/V·s for the IGZO device with a metal-induced polycrystalline channel formed at 300 °C compared to 18.1 cm2/V·s for an amorphous IGZO TFT without a catalytic layer. This work proposes a facile and effective route to enhance device performance by crystallizing the IGZO layer with standard annealing temperatures, without the introduction of expensive laser irradiation processes.

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Section: Resultssupporting

confidence: 92%

The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer

Shin

Kim

et al. 2017

Sci Rep

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“…Annealing at higher temperatures over 600 °C causes crystallization, as shown in Figure . Note that the structural relaxation depends on the as‐deposited states.…”

Section: Defect Reduction Creation Structural Relaxation and Crystmentioning

confidence: 93%

Electronic Defects in Amorphous Oxide Semiconductors: A Review

Ide

Nomura

Hosono

et al. 2019

Physica Status Solidi (a)

200

191

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Amorphous oxide semiconductors (AOSs) have been commercialized since 2012 as thin-film transistor (TFT) backplanes in flat-panel displays. This review first provides a brief history and current status of AOS technology, and then introduces electronic defects in AOSs reported to date that are critically important for understanding and controlling the instability of TFTs that is the most serious issue in the development of the AOS technology. In particular, it is important to know that many AOS defects are related to oxygen and hydrogen impurities, though oxygen is the major constituent of AOS and hydrogen is not intentionally incorporated. Instability issues and their underlying mechanisms are also discussed in relation to these defects.

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“…Furthermore, many experimental studies have explored the relationship between solid-phase crystallization and the performance of the device with amorphous In 2 O 3 -based films. For example, amorphous structures and the generation of nano- to microsized crystallites with preferred crystallographic orientations have been discussed to improve the stability and performance of amorphous IGZO TFT devices. − The chemical composition in amorphous IGZO films also has been reported to act as a key role to control the device stability, e.g., indium-rich IGZO compositions give rise to a good device stability after annealing at 150 °C. , Therefore, by understanding the crystallization mechanism of amorphous oxide films and their related physical properties, we can gain new insights for designing annealing treatments and preventing the deterioration of multifunctional flexible electronics.…”

Section: Introductionmentioning

confidence: 99%

Temporal Evolution of Microscopic Structure and Functionality during Crystallization of Amorphous Indium-Based Oxide Films

Jia

Iwasaki

Yamamoto

et al. 2021

ACS Appl. Mater. Interfaces

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Understanding the crystallization mechanism of amorphous metal-oxide thin films remains of importance to avoid the deterioration of multifunctional flexible electronics. We derived the crystallization mechanism of indium-based functional amorphous oxide films by using in situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. Crystallization begins with surface nucleation, especially at low annealing temperatures, and proceeds simultaneous nucleation and growth in the bulk. Three-dimensional crystal growth in the film was observed when the crystallite size was sufficiently smaller than the film thickness. When the growing crystallites reached the film surface, the crystallization was dominated by two- or lower-dimensional growth. Such crystallization can be explained within the framework of the modified Avrami theory and can be varied for tailoring the electrical properties of the amorphous In2O3 film. After tailoring the film crystallinity and crystallite size, the carrier mobility was improved to >100 cm2/V·s in 30 min. Our results show that a carrier mobility of >90 cm2/V·s can be implemented for the In2O3 film with a crystallinity of >40% and a crystallite size of >70 nm by an optimized annealing process. The incorporation of Ga element into amorphous In2O3 films obviously increases the activation energy of nucleation and migration. In contrast, Sn dopants can promote the crystal growth. This is attributed to two kinds of migration mechanisms during the annealing in air, one of which is the dominant migration mechanism of oxygen interstitials in crystallized indium–tin oxide (ITO) films and the other dominated by oxygen vacancies in In2O3 and IGO films. Combining the modified Avrami theory with TEM observations, we predicted the structural evolution kinetics for indium-based amorphous oxide films and gained new insights for understanding the temporal structure–functionality relationship during crystallization.

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Crystallization behavior of amorphous indium–gallium–zinc-oxide films and its effects on thin-film transistor performance

Cited by 23 publications

References 18 publications

The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer

The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer

Electronic Defects in Amorphous Oxide Semiconductors: A Review

Temporal Evolution of Microscopic Structure and Functionality during Crystallization of Amorphous Indium-Based Oxide Films

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