Thermal and plasma enhanced atomic layer deposition of ultrathin TiO2 on silicon from amide and alkoxide precursors: growth chemistry and photoelectrochemical performance.

Abstract Due to its low cost and suitable band gap, silicon has been studied as a photoanode material for some time. However, as a result of poor stability during the oxygen evolution reaction (OER), Si still remains unsuitable for any extended use. Ultra-thin titanium dioxide (TiO2) films have been used as protective coatings and are shown to enhance Si photoanode lifetime with added solar to hydrogen (STH) performance improvements through distancing the oxidation reaction away from the Si photoanode surface and improved charge transport through the anode. This study details the nucleation, growth chemistry, and performance of TiO2 thin films prepared via thermal and plasma enhanced atomic layer deposition (ALD) using both titanium isopropoxide (TTIP) and Tetrakis(dimethylamido)titanium (TDMAT) as the precursor material. The effect of post ALD treatments of plasma and air annealing was also studied. Films were investigated using photoelectrochemical cell testing to evaluate photoelectrochemical performance, and in-vacuum cycle-by-cycle x-ray photoelectron spectroscopy (XPS) was used as the primary characterisation technique to study nucleation mechanisms and film properties contributing to improvements in cell performance. TiO2 grown by plasma enhanced ALD results in cleaner films with reduced carbon incorporation. However, despite increased carbon incorporation, thermally grown films showed improved photocurrent as a result of oxygen vacancies in these films. Post deposition annealing in a H2 ambient is shown to further improve photocurrent in all cases, while annealing in atmosphere leads to uniform film chemistry and enhanced photocurrent stability in all cases.

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Plasma Enhanced Atomic Layer Deposition of Tantalum (V) Oxide

Coatings ◽

10.3390/coatings11101206 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1206

Author(s):

Pavel Fedorov ◽

Denis Nazarov ◽

Oleg Medvedev ◽

Yury Koshtyal ◽

Aleksander Rumyantsev ◽

...

Keyword(s):

Thin Films ◽

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Protective Coatings ◽

Lithium Ion ◽

Atomic Layer ◽

Evaporator Temperature ◽

Current Increase ◽

X Ray ◽

Layer Deposition

The tantalum oxide thin films are promising materials for various applications: as coatings in optical devices, as dielectric layers for micro and nanoelectronics, and for thin-films solid-state lithium-ion batteries (SSLIBs). This article is dedicated to the Ta-O thin-film system synthesis by the atomic layer deposition (ALD) which allows to deposit high quality films and coatings with excellent uniformity and conformality. Tantalum (V) ethoxide (Ta(OEt)5) and remote oxygen plasma were used as tantalum-containing reagent and oxidizing co-reagent, respectively. The influence of deposition parameters (reactor and evaporator temperature, pulse and purge times) on the growth rate were studied. The thickness of the films were measured by spectroscopic ellipsometry, scanning electron microscopy and X-ray reflectometry. The temperature range of the ALD window was 250–300 °C, the growth per cycle was about 0.05 nm/cycle. Different morphology of films deposited on silicon and stainless steel was found. According to the X-ray diffraction data, the as-prepared films were amorphous. But the heat treatment study shows crystallization at 800 °C with the formation of the polycrystalline Ta2O5 phase with a rhombic structural type (Pmm2). The results of the X-ray reflectometry show the Ta-O films’ density is 7.98 g/cm3, which is close to the density of crystalline Ta2O5 of the rhombic structure (8.18 g/cm3). The obtained thin films have a low roughness and high uniformity. The chemical composition of the surface and bulk of Ta-O coatings was studied by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. Surface of the films contain Ta2O5 and some carbon contamination, but the bulk of the films does not contain carbon and any precursor residues. Cyclic voltammetry (CVA) showed that there is no current increase for tantalum (V) oxide in a potential window of 3–4.2 V and has prospects of use as protective coatings for cathode materials of SSLIBs.

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One-Dimensional TiO2@GaON Core-Shell Nanowires with Controlled Shell Thickness from Atomic Layer Deposition for Stable and Efficient Photoelectrochemical Water Splitting

10.26434/chemrxiv.9199796 ◽

2019 ◽

Author(s):

Jiajia Tao ◽

Hong-Ping Ma ◽

Kaiping Yuan ◽

Yang Gu ◽

Jianwei Lian ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Band Gap ◽

Water Splitting ◽

Atomic Layer ◽

Photoelectrochemical Water Splitting ◽

Core Shell ◽

Photoelectrochemical Performance ◽

Highly Efficient ◽

Layer Deposition ◽

Shell Nanowires

<div>As a promising oxygen evolution reaction semiconductor, TiO2 has been extensively investigated for solar photoelectrochemical water splitting. Here, a highly efficient and stable strategy for rationally preparing GaON cocatalysts on TiO2 by atomic layer deposition is demonstrated, which we show significantly enhances the</div><div>photoelectrochemical performance compared to TiO2-based photoanodes. For TiO2@20 nm-GaON core-shell nanowires a photocurrent density up to 1.10 mA cm-2 (1.23 V vs RHE) under AM 1.5 G irradiation (100 mW cm-2) has been achieved, which is 14 times higher than that of TiO2 NWs. Furthermore, the oxygen vacancy formation on GaON as well as the band gap matching with TiO2 not only provides more active sites for water oxidation but also enhances light absorption to promote interfacial charge separation and migration. Density functional theory studies of model systems of GaON-modified TiO2 confirm the band gap reduction, high reducibility and ability to activate water. The highly efficient and stable systems of TiO2@GaON core-shell nanowires provide a deeper understanding and universal strategy for enhancing photoelectrochemical performance of photoanodes now available. </div>

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Phase-gradient atomic layer deposition of TiO2 thin films by plasma-induced local crystallization

Ceramics International ◽

10.1016/j.ceramint.2021.07.037 ◽

2021 ◽

Author(s):

Dohyun Go ◽

Jaehyeong Lee ◽

Jeong Woo Shin ◽

Sungje Lee ◽

Wangu Kang ◽

...

Keyword(s):

Thin Films ◽

Atomic Layer Deposition ◽

Atomic Layer ◽

Tio2 Thin Films ◽

Phase Gradient ◽

Layer Deposition

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Structural and Optical Properties of Luminescent Copper(I) Chloride Thin Films Deposited by Sequentially Pulsed Chemical Vapour Deposition

Coatings ◽

10.3390/coatings8100369 ◽

2018 ◽

Vol 8 (10) ◽

pp. 369 ◽

Cited By ~ 1

Author(s):

Richard Krumpolec ◽

Tomáš Homola ◽

David Cameron ◽

Josef Humlíček ◽

Ondřej Caha ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Chemical Vapour Deposition ◽

Photoelectron Spectroscopy ◽

Vapour Deposition ◽

Chemical Vapour ◽

Atomic Layer ◽

Nanocrystalline Films ◽

Zinc Blende ◽

Layer Deposition

Sequentially pulsed chemical vapour deposition was used to successfully deposit thin nanocrystalline films of copper(I) chloride using an atomic layer deposition system in order to investigate their application to UV optoelectronics. The films were deposited at 125 °C using [Bis(trimethylsilyl)acetylene](hexafluoroacetylacetonato)copper(I) as a Cu precursor and pyridine hydrochloride as a new Cl precursor. The films were analysed by XRD, X-ray photoelectron spectroscopy (XPS), SEM, photoluminescence, and spectroscopic reflectance. Capping layers of aluminium oxide were deposited in situ by ALD (atomic layer deposition) to avoid environmental degradation. The film adopted a polycrystalline zinc blende-structure. The main contaminants were found to be organic materials from the precursor. Photoluminescence showed the characteristic free and bound exciton emissions from CuCl and the characteristic exciton absorption peaks could also be detected by reflectance measurements.

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The initial atomic layer deposition of HfO2∕Si(001) as followed in situ by synchrotron radiation photoelectron spectroscopy

Journal of Applied Physics ◽

10.1063/1.2978362 ◽

2008 ◽

Vol 104 (6) ◽

pp. 064116 ◽

Cited By ~ 26

Author(s):

Massimo Tallarida ◽

Konstantin Karavaev ◽

Dieter Schmeisser

Keyword(s):

Synchrotron Radiation ◽

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Atomic Layer ◽

Layer Deposition

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Nucleation Studies of HfO2 Thin Films Produced by Atomic Layer Deposition

MRS Proceedings ◽

10.1557/proc-0996-h03-09 ◽

2007 ◽

Vol 996 ◽

Author(s):

Justin C. Hackley ◽

J. Derek Demaree ◽

Theodosia Gougousi

Keyword(s):

Thin Films ◽

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Flow Reactor ◽

Atomic Layer ◽

Sample Surface ◽

Interfacial Region ◽

Initial Growth ◽

Layer Deposition ◽

Similar Growth

AbstractA hot wall Atomic Layer Deposition (ALD) flow reactor equipped with a Quartz Crystal Microbalance (QCM) has been used for the deposition of HfO2 thin films with tetrakis (dimethylamino) hafnium (TDMAH) and H2O as precursors. HfO2 films were deposited on H-terminated Si and SC1 chemical oxide starting surfaces. Spectroscopic ellipsometry (SE) and QCM measurements confirm linear growth of the films at a substrate temperature of 275°C. FTIR spectra indicate the films are amorphous as-deposited. Two distinct growth regimes are observed: from 1-50 cycles, both surfaces display similar growth rates of about 1.0Å/cycle; from 50-200 cycles, HfO2 growth is decreased by about 15% to ~0.87Å/cycle on both surfaces. Nucleation and initial growth behavior of the films on Si-H were examined using X-ray photoelectron spectroscopy (XPS). Angle-resolved XPS, at take-off angles of θ=0, 15, 30, 45 and 60° measured from the normal to the sample surface, is used to probe the interfacial region of thin films (4, 7, 10, 15 and 25 cycles) on H-terminated samples. Initially, an interfacial layer comprised of a SiOx/HfSiOx mixture is grown between 1-10 ALD cycles. We observe that the Si/HfO2 interface is unstable, and oxidation continues up to the 25th ALD cycle, reaching a thickness of ~18Å.

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Growth Temperature Dependence of TiO2 Thin Films Prepared by Using Plasma-Enhanced Atomic Layer Deposition Method

Journal of the Korean Physical Society ◽

10.3938/jkps.50.1827 ◽

2007 ◽

Vol 50 (6) ◽

pp. 1827 ◽

Cited By ~ 22

Author(s):

G. X. Liu ◽

F. K. Shan ◽

W. J. Lee ◽

B. C. Shin

Keyword(s):

Thin Films ◽

Atomic Layer Deposition ◽

Temperature Dependence ◽

Growth Temperature ◽

Atomic Layer ◽

Deposition Method ◽

Tio2 Thin Films ◽

Layer Deposition ◽

Atomic Layer Deposition Method ◽

Growth Temperature Dependence

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Air Annealing Effect on Oxygen Vacancy Defects in Al-doped ZnO Films Grown by High-Speed Atmospheric Atomic Layer Deposition

Molecules ◽

10.3390/molecules25215043 ◽

2020 ◽

Vol 25 (21) ◽

pp. 5043

Author(s):

Chia-Hsun Hsu ◽

Xin-Peng Geng ◽

Wan-Yu Wu ◽

Ming-Jie Zhao ◽

Xiao-Ying Zhang ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Band Gap ◽

Photoelectron Spectroscopy ◽

High Speed ◽

Oxygen Vacancies ◽

Annealing Temperature ◽

Atomic Layer ◽

Zno Films ◽

X Ray ◽

Layer Deposition

In this study, aluminum-doped zinc oxide (Al:ZnO) thin films were grown by high-speed atmospheric atomic layer deposition (AALD), and the effects of air annealing on film properties are investigated. The experimental results show that the thermal annealing can significantly reduce the amount of oxygen vacancies defects as evidenced by X-ray photoelectron spectroscopy spectra due to the in-diffusion of oxygen from air to the films. As shown by X-ray diffraction, the annealing repairs the crystalline structure and releases the stress. The absorption coefficient of the films increases with the annealing temperature due to the increased density. The annealing temperature reaching 600 °C leads to relatively significant changes in grain size and band gap. From the results of band gap and Hall-effect measurements, the annealing temperature lower than 600 °C reduces the oxygen vacancies defects acting as shallow donors, while it is suspected that the annealing temperature higher than 600 °C can further remove the oxygen defects introduced mid-gap states.

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Development of High-Quality Gate Oxide on 4H-SiC Using Atomic Layer Deposition

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1004.547 ◽

2020 ◽

Vol 1004 ◽

pp. 547-553

Author(s):

A.B. Renz ◽

Oliver J. Vavasour ◽

Peter M. Gammon ◽

Fan Li ◽

Tian Dai ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Elevated Temperatures ◽

Dielectric Breakdown ◽

Atomic Layer ◽

Oxide Semiconductor ◽

Gas Treatment ◽

Time Dependent Dielectric Breakdown ◽

Layer Deposition ◽

Order Of Magnitude

A systematic post-deposition annealing study on Silicon Carbide (SiC) metal-oxide-semiconductor capacitors (MOSCAPs) using atomic layer deposition (ALD)-deposited silicon dioxide (SiO2) layers was carried out. Anneals were done in oxidising (N2O), inert (Ar) and reducing (H2:N2) ambients at elevated temperatures from 900°C to 1300°C for 1 hour. Electrical characterisation results show that the forming gas treatment at 1100°C reduces the flatband voltage to 0.23 V from 10 V for as-deposited SiO2 layers. The density of interface traps (DIT) was also reduced by one order of magnitude to 2×1011 cm-2 eV-1 at EC-ET = 0.2 eV. As an indicator of the improvement, characterisation by x-ray photoelectron spectroscopy (XPS) showed that silicon enrichment present in as-deposited layers was largely reduced by the forming gas anneal, improving the stoichiometry. Time-dependent dielectric breakdown (TDDB) results showed that the majority of forming gas annealed samples broke down at breakdown fields of 12.5 MV × cm-1, which is about 2.5 MV × cm-1 higher than for thermally oxidised samples.

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