(Invited) The Behavior of C-axis-aligned A-b-plane-anchored Crystal (CAA Crystal)

Yamazaki, Shunpei

doi:10.1149/06701.0029ecst

Cited by 9 publications

(10 citation statements)

References 15 publications

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“…Further growth of the nanoclusters occurs in the a−b plane direction because In, Ga, Zn, and O ions are more likely to be adsorbed on the side of nanoclusters. 54 As the migration of ions to preferential adsorption positions is activated by temperature, large CAAC domains are formed at a higher T sub of 300 °C, whereas only small crystalline nanoclusters surrounded by a-IGZO are formed at T sub = 200 °C (inset of Figure 3a). We presume that the lateral growth of these clusters is suppressed by insufficient migration of ions to preferential adsorption positions at lower T sub , while a less-ordered amorphous structure was predominantly formed.…”

Section: Resultsmentioning

confidence: 80%

“…These nanoclusters have a (GaZn)O/InO 2 /(GaZn)O layered structure along the c -axis, which aligns perpendicular to the substrate surface. Further growth of the nanoclusters occurs in the a – b plane direction because In, Ga, Zn, and O ions are more likely to be adsorbed on the side of nanoclusters . As the migration of ions to preferential adsorption positions is activated by temperature, large CAAC domains are formed at a higher T sub of 300 °C, whereas only small crystalline nanoclusters surrounded by a-IGZO are formed at T sub = 200 °C (inset of Figure a).…”

Section: Resultsmentioning

confidence: 99%

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Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Glushkova

Dekkers

Nag

et al. 2021

ACS Appl. Electron. Mater.

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In an effort to fabricate In–Ga–Zn oxide (IGZO) thin-film transistors (TFTs) that combine high performance and high stability, we optimize sputtering conditions to create devices based on different IGZO phases: amorphous, c-axis-aligned crystalline (CAAC), and a transition between them, which is introduced here as protocrystalline IGZO. For this, we study the performance of TFTs based on thin films of IGZO sputtered at different substrate temperatures T sub and oxygen flow ratios R O2 . While T sub is the principal phase-determining parameter, R O2 can be further optimized to enhance IGZO TFT characteristics. For both amorphous IGZO and CAAC IGZO, the best TFT performance and the best TFT bias stress stability are found under different sputtering conditions. In contrast, the protocrystalline IGZO shows a convergence of the highest TFT performance and the best bias stress stability, observed for an IGZO film sputtered at T sub = 200 °C and R O2 = 20%.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Glushkova

Dekkers

Nag

et al. 2021

ACS Appl. Electron. Mater.

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“…The orientations successively change between grains, as indicated by color changes, for example, from red to purple or from purple to blue in the color-mapping image. 21) This crystallinity appears to be clearly different from the single-crystal and polycrystalline structures, which probably corresponds to the fact that CAAC- IGZO is unlikely to induce degradation of the electrical characteristics due to grain boundaries, which is a problem of polycrystals. In CAAC-IGZO, nanoparticles are microscopically arranged at the substrate surface, but are not fully bonded to each other as in single-crystal IGZO.…”

Section: Crystallinity and Composition Analyses Of Os Filmsmentioning

confidence: 99%

Achievement of a high-mobility FET with a cloud-aligned composite oxide semiconductor

Yamazaki

Shima²,

Hosaka³

et al. 2016

Jpn. J. Appl. Phys.

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We have recently discovered that films of a widely used In–Ga–Zn oxide (IGZO) with have different material composition states when sputter-deposited under different conditions using the same polycrystalline IGZO target. Significant improvements in on-state current and mobility (as high as 40 cm2·V−1·s−1) are obtained. The results of local composition analysis indicate that the deposited film is not composed of any known homogeneous IGZO compound and that the components of this film are separated into two types of nanoparticle regions: one type is composed mainly of GaO x and GaZnO x , which contribute to on/off (switching) characteristics, and the other is composed mainly of InO x and InZnO x , which contribute to on-state characteristics. These regions constitute a new type of oxide semiconductor (OS) film. The nanoparticles with a blurry boundary extend like a cloud, probably complementing one another. We consider that this OS film has a novel composition, which can be described as a “cloud-aligned composite OS” (CAC-OS).

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“…Figure shows analysis results of the CAAC‐IGZO using a Voronoi diagram, and the results indicate that the crystal grains are connected in a continuous manner …”

Section: Caac‐igzomentioning

confidence: 99%

“…Figure 7 shows analysis results of the CAAC-IGZO using a Voronoi diagram, and the results indicate that the crystal grains are connected in a continuous manner. 28 Formation of the Voronoi diagram ( Figure 8) is explained. First, lattice points were extracted by analyzing the TEM image ( Figure 8A), adjacent lattice points were connected with segments ( Figure 8B), and a vertical bisector of each segment was drawn ( Figure 8C) to obtain points where perpendicular bisectors intersect (ie, Voronoi points) ( Figure 8D).…”

Section: Caac-igzomentioning

confidence: 99%

Crystalline IGZO ceramics (crystalline oxide semiconductor)–based devices for artificial intelligence

Yamazaki

Ohshita

Oota

et al. 2019

Int J Ceramic Engine & Sci

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In 2009, a crystalline oxide semiconductor with a layered structure, which we refer to as c‐axis–aligned crystalline indium‐gallium‐zinc oxide (CAAC‐IGZO), was first discovered. CAAC‐IGZO has a peculiar crystal structure in which clear grain boundaries are not observed despite high c‐axis alignment and absence of a‐b plane alignment. When compared to a Si field‐effect transistor (FET), a metal‐oxide‐semiconductor (MOS) FET, utilizing CAAC‐IGZO, presents lower off‐state current (on the order of yA [10−24 A]). These unique characteristics allow CAAC‐IGZO to realize devices with low power consumption. With the emerging era of artificial intelligence, wherein power saving becomes more significant, CAAC‐IGZO has attracted attention as a potential replacement for Si. This paper describes the characteristics and potentials of CAAC‐IGZO for the development of memory devices with unprecedented functions.

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(Invited) The Behavior of C-axis-aligned A-b-plane-anchored Crystal (CAA Crystal)

Cited by 9 publications

References 15 publications

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Achievement of a high-mobility FET with a cloud-aligned composite oxide semiconductor

Crystalline IGZO ceramics (crystalline oxide semiconductor)–based devices for artificial intelligence

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