The Influence of Ga–OH Bond at Initial GaN Surface on the Electrical Characteristics of SiO<sub>2</sub>/GaN Interface

Uenuma, Mutsunori; Ando, Ryo; Furukawa, Masaaki; Uraoka, Yukiharu

doi:10.1002/pssb.201900368

Cited by 9 publications

(9 citation statements)

References 29 publications

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“…All spectra feature two peaks shifted by approximately 1.5 eV. This peak separation is consistent with previous studies (0.6–1.5 eV). − The peaks are located at 530.5 and 531.9 eV and denote the Ga–O (attributed to the O 2– anions of the crystalline network) and Ga–OH (oxides with lower electron density, i.e., O – or OH – , and greater covalent character) components, respectively. As-made galinstan microdroplets feature a high abundance of the Ga–O component (denoting the native gallium oxide).…”

Section: Resultssupporting

confidence: 88%

GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

et al. 2022

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Gallium-based liquid metals form alloys with a melting point close to or below room temperature. On the surface of these liquid metals, a thin oxide skin is formed once in contact with oxygen, and this oxide skin can be leveraged to stabilize liquid metal micro- and nanodroplets in a liquid. During sonication and storage of these droplets in aqueous solution, gallium oxide hydroxide (GaOOH) forms on these droplets, and given enough time or treatment with heat, a full shape transition and dealloying are observed. In this article, we show that GaOOH can be grown at room temperature and that the growth is dependent on both the local environment and temperature. GaOOH growth on liquid metal microdroplets located at the air/water interface is considerably faster than in the bulk phase. Interestingly, hydrolysis to GaOOH is hampered and stops at 15 °C in bulk water after 6 h. In contrast, hydrolysis commences even at 15 °C for liquid metal microdroplets located at the air/water interface, and full surface coverage is obtained after around 24 h (compared to 12 h at 25 °C at the air/water interface). The X-ray photoelectron spectroscopy (XPS) measurement suggests that gallium oxide is dissolved and Ga(OH)3 is formed as a precursor that reacts in a downstream reaction toward GaOOH. This improved understanding of the GaOOH formation can be leveraged to control the liquid metal micro- and nanodroplet shape and composition (i.e., for biomedical applications).

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Section: Resultssupporting

confidence: 88%

GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

et al. 2022

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“…(We note that the presence of some adsorbed water cannot be excluded.) The energy difference between the hydroxide and oxide peaks was within the reported range (0.6–1.5 eV). ,− The total oxygen coverage corresponds to an areal density of 1.5 × 10 15 cm –2 (Table ). This points to a thin surface layer with a thickness close to that of a monolayer.…”

Section: Results and Discussionsupporting

confidence: 63%

Chemical Etching of GaN in KOH Solution: Role of Surface Polarity and Prior Photoetching

et al. 2022

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Surface polarity plays a significant role in chemical etching of GaN in KOH solution, a process that is important for quality control and device fabrication. In this work, basic chemical mechanisms are proposed to explain the role of surface orientation in the chemical etching of the semiconductor. In addition, it is shown how prior photoetching of inert surfaces [the polar (0001), semipolar (101̅ 1̅ ), and nonpolar (11̅ 00) interfaces] enables chemical etching. Photoetching gives rise to the formation of nanocolumns on dislocations and to protrusions on nanoscale inhomogeneities. Subsequent etching in KOH solution leads to the development of distinctive features that depend on the crystal orientation of the surface and the presence of the inhomogeneities. The morphology of the photoetched surfaces was revealed by scanning electron microscopy, while X-ray photoelectron spectroscopy measurements were used to investigate the surface chemistry of these processes.

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“…In this study, our objectives are GaN power semiconductor devices, which have attracted much attention in recent years, while many issues still remain at the MOS interface. 11,12 One of the challenges is how to reduce the electrical interface defects measured by the interface state density, D it , which represents the quality of an interface. D it is strongly affected by the surface condition of the GaN substrate and the deposition conditions of plasma-enhanced chemical vapor deposition (PECVD), which deposits SiO 2 .…”

Section: ■ Introductionmentioning

confidence: 99%

“…D it is strongly affected by the surface condition of the GaN substrate and the deposition conditions of plasma-enhanced chemical vapor deposition (PECVD), which deposits SiO 2 . For improving the surface of GaN, previous research reported a significant reduction of D it values by introducing the operation of UV/O 3 treatment to the surface of GaN . As deposition conditions for PECVD, five process variables exist: temperature, pressure, radio frequency (RF) power, oxygen flow rate, and precursor material (TEOS) flow rate.…”

Section: Introductionmentioning

confidence: 99%

Interface State Density Prediction between an Insulator and a Semiconductor by Gaussian Process Regression Models for a Modified Process

Matsunaga

Harada

et al. 2023

ACS Omega

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During data-driven process condition optimization on a laboratory scale, only a small-size data set is accessible and should be effectively utilized. On the other hand, during process development, new operations are frequently inserted or current operations are modified. These accessible data sets are somewhat related but not exactly the same type. In this study, we focus on the prediction of the quality of the interface between an insulator and GaN as a semiconductor for the potential application of GaN power semiconductor devices. The quality of the interface was represented as the interface state density, D it, and the inserted operation to the process was the ultraviolet (UV)/O3-gas treatment. Our retrospective evaluation of model-building approaches for D it prediction from a process condition revealed that for the UV/O3-treated interfaces, data of interfaces without the treatment contributed to performance improvement. Such performance improvement was not observed when using a data set of Si as the semiconductor. As a modeling method, the automatic relevance vector-based Gaussian process regression with the prior distribution of the length-scale parameters exhibited a relatively high predictive performance and represented a reasonable uncertainty of prediction as reflected by the distance to the training data set. This feature is a prerequisite for a potential application of Bayesian optimization. Furthermore, hyperparameters in the prior distribution of the length-scales could be optimized by leave-one-out cross-validation.

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The Influence of Ga–OH Bond at Initial GaN Surface on the Electrical Characteristics of SiO₂/GaN Interface

Cited by 9 publications

References 29 publications

GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

Chemical Etching of GaN in KOH Solution: Role of Surface Polarity and Prior Photoetching

Interface State Density Prediction between an Insulator and a Semiconductor by Gaussian Process Regression Models for a Modified Process

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The Influence of Ga–OH Bond at Initial GaN Surface on the Electrical Characteristics of SiO2/GaN Interface

Cited by 9 publications

References 29 publications

GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

Chemical Etching of GaN in KOH Solution: Role of Surface Polarity and Prior Photoetching

Interface State Density Prediction between an Insulator and a Semiconductor by Gaussian Process Regression Models for a Modified Process

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The Influence of Ga–OH Bond at Initial GaN Surface on the Electrical Characteristics of SiO₂/GaN Interface