Influence of the Al2O3partial-monolayer number on the crystallization mechanism of TiO2in ALD TiO2/Al2O3nanolaminates and its impact on the material properties

Testoni, G. E.; Chiappim, William; Pessoa, Rodrigo Sávio; Fraga, Mariana Amorim; Miyakawa, Walter; Sakane, Kumiko Koibuchi; Galvão, Nierlly Karinni de Almeida Maribondo; Vieira, Lúcia; Maciel, Homero Santiago

doi:10.1088/0022-3727/49/37/375301

Cited by 34 publications

(29 citation statements)

References 44 publications

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“…After HCHP treatment, the same spectrum presented a redshift (~0.7 eV) and now it can be deconvoluted in three curves, Five vibrational modes for both pristine and black TiO 2 films can be observed: E g (located around 139.5 cm −1 , 199.0 cm −1 , and 632.6 cm −1 ), B 1g (~390.5 cm −1 ), and A 1g /B 1g (~513.3 cm −1 ) (see Figure 4a). These vibration modes are relative to the anatase phase [41,42], corroborating the x-ray diffraction results. Moreover, the heating of the sample during the HCHP process, which reached the temperature of about 260 • C, was not sufficient to initiate the formation of the rutile phase.…”

Section: Structural and Chemical Propertiessupporting

confidence: 84%

Black TiO2 Thin Films Production Using Hollow Cathode Hydrogen Plasma Treatment: Synthesis, Material Characteristics and Photocatalytic Activity

et al. 2020

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Black TiO2 materials have been quite widely explored due to their large solar absorption and superior photocatalytic activity. In this paper, the blackening process of titanium dioxide (TiO2) thin film using the hollow cathode hydrogen plasma (HCHP) technique is reported. First, pristine anatase TiO2 films were grown by magnetron sputtering onto silicon and cover glass substrates and then annealed at 450 °C for 2 h. Then, the as-grown TiO2 films were treated with HCHP for 15 min. The physical, chemical and morphological properties of the films were analyzed by profilometry, X-ray diffraction (XRD), UV-Vis spectrophotometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. Electrical and photocatalytic measurements were performed by four-point probe and methylene blue UV degradation assays, respectively. The results showed that the black TiO2 film is highly absorbent in the UV-visible region, has low electrical resistance and greater surface area compared to the non-treated TiO2 film. These properties of black TiO2 film, as well as its performance as a photocatalytic agent, were investigated, indicating the superior quality of this material in thin film form and the promising potential of the HCHP treatment to produce hydrogenated TiO2 in short process time.

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Section: Structural and Chemical Propertiessupporting

confidence: 84%

Black TiO2 Thin Films Production Using Hollow Cathode Hydrogen Plasma Treatment: Synthesis, Material Characteristics and Photocatalytic Activity

et al. 2020

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“…The thickness of the composite TiAlO layer and Al 2 O 3 blocking layer are ~14 and 16.5 nm, respectively. The TiO 2 /Al 2 O 3 mixture under high temperature has been reported by other researchers [15–17]. For example, in work by Mikhelashvili et al [16] after annealing at 950 °C, the Al 2 O 3 -TiO 2 nanolaminates transformed into a TiAlO layer with a nearly uniform distribution of Al and Ti oxides across the structure.…”

Section: Resultssupporting

confidence: 52%

Electronic Structure and Charge-Trapping Characteristics of the Al2O3-TiAlO-SiO2 Gate Stack for Nonvolatile Memory Applications

Yang

Tang

et al. 2017

Nanoscale Res Lett

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In this work, high-k composite TiAlO film has been investigated as charge-trapping material for nonvolatile memory applications. The annealing formed Al2O3-TiAlO-SiO2 dielectric stack demonstrates significant memory effects and excellent reliability properties. The memory device exhibits a large memory window of ~2.6 V under ±8 V sweeping voltage, and it shows only ~14% charge loss after more than 10 years’ retention, indicating excellent charge retention properties. The electronic structures of the Al2O3-TiAlO-SiO2 have been studied by X-ray photoelectron spectroscopy measurements, and it reveals that the quantum well and the defect traps in TiAlO film can provide a >1.8 eV deep barrier for charge confinement in the TiAlO layer. The mixing between Al2O3 and TiO2 can increase the defects related to the under-coordinated Ti3+ atoms, thereby enhancing the charge-trapping efficiency of the device. Our work implies that high-k TiAlO composite film is promising for applications in future nonvolatile charge-trapping memories.

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“…TiO 2 /Al 2 O 3 nanolaminate structure was prepared, using the design proposed by Testoni et al [49], i.e., alternatively depositing a TiO 2 sublayer and Al 2 O 3 partial-monolayer, respectively, in "n" supercycles. The Al 2 O 3 is formed by a single cycle of trimethylaluminum (TMA)-O 2 plasma, so it is a partial-monolayer because of steric hindrance of the precursors, while the TiO 2 sublayer is formed by repeating 60 cycles of TTIP-O 2 plasma.…”

Section: Nanolaminate Preparationmentioning

confidence: 99%

“…The Al 2 O 3 is formed by a single cycle of trimethylaluminum (TMA)-O 2 plasma, so it is a partial-monolayer because of steric hindrance of the precursors, while the TiO 2 sublayer is formed by repeating 60 cycles of TTIP-O 2 plasma. This condition is in the interface of the TiO 2 crystallization disruption [49]. Here, the Al 2 O 3 partial-monolayers were grown, using TMA (97%, Sigma-Aldrich, São Paulo, Brazil) at 21 • C and O 2 plasma.…”

Section: Nanolaminate Preparationmentioning

confidence: 99%

MOS Capacitance Measurements for PEALD TiO2 Dielectric Films Grown under Different Conditions and the Impact of Al2O3 Partial-Monolayer Insertion

et al. 2020

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In this paper, we report the plasma-enhanced atomic layer deposition (PEALD) of TiO2 and TiO2/Al2O3 nanolaminate films on p-Si(100) to fabricate metal-oxide-semiconductor (MOS) capacitors. In the PEALD process, we used titanium tetraisopropoxide (TTIP) as a titanium precursor, trimethyl aluminum (TMA) as an aluminum precursor and O2 plasma as an oxidant, keeping the process temperature at 250 °C. The effects of PEALD process parameters, such as RF power, substrate exposure mode (direct or remote plasma exposure) and Al2O3 partial-monolayer insertion (generating a nanolaminate structure) on the physical and chemical properties of the TiO2 films were investigated by Rutherford backscattering spectroscopy (RBS), Raman spectroscopy, grazing incidence X-ray diffraction (GIXRD), and field emission scanning electron microscopy (FESEM) techniques. The MOS capacitor structures were fabricated by evaporation of Al gates through mechanical mask on PEALD TiO2 thin film, followed by evaporation of an Al layer on the back side of the Si substrate. The capacitors were characterized by current density-voltage (J-V), capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Our results indicate that RF power and exposure mode promoted significant modifications on the characteristics of the PEALD TiO2 films, while the insertion of Al2O3 partial monolayers allows the synthesis of TiO2/Al2O3 nanolaminate with well-spaced crystalline TiO2 grains in an amorphous structure. The electrical characterization of the MOS structures evidenced a significant leakage current in the accumulation region in the PEALD TiO2 films, which could be reduced by the addition of partial-monolayers of Al2O3 in the bulk of TiO2 films or by reducing RF power.

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Influence of the Al₂O₃partial-monolayer number on the crystallization mechanism of TiO₂in ALD TiO₂/Al₂O₃nanolaminates and its impact on the material properties

Cited by 34 publications

References 44 publications

Black TiO2 Thin Films Production Using Hollow Cathode Hydrogen Plasma Treatment: Synthesis, Material Characteristics and Photocatalytic Activity

Black TiO2 Thin Films Production Using Hollow Cathode Hydrogen Plasma Treatment: Synthesis, Material Characteristics and Photocatalytic Activity

Electronic Structure and Charge-Trapping Characteristics of the Al2O3-TiAlO-SiO2 Gate Stack for Nonvolatile Memory Applications

MOS Capacitance Measurements for PEALD TiO2 Dielectric Films Grown under Different Conditions and the Impact of Al2O3 Partial-Monolayer Insertion

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