A systematical investigation of layer growth rate, impurity level and morphology evolution in TiO2 thin films grown by ALD between 100 and 300 °C

Xia, Bingbing; Ganem, J.‐J.; Briand, Emrick; Baron-Wiechec, A.; Vickridge, Ian

doi:10.1016/j.vacuum.2023.112408

Cited by 6 publications

(3 citation statements)

References 58 publications

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“…The high TDMAT/ H 2 O/air ALD GPC at 220 °C likely has a primary contribution from TDMAT decomposition. This decomposition typically would result in CVD-like deposition, which can increase the GPC due to the gas phase, non-surface limited reactions, as consistent with Xia et al [38]. We propose that during TDMAT/H 2 O/air ALD at 220 °C, competing reactions occur between TDMAT decomposition and surface adsorption and reaction, increasing the film growth rate and reducing anatase crystallization.…”

Section: Tdmat/h 2 O/air Ald Overviewsupporting

confidence: 87%

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing

Wooding,

Kalaitzidou,

Losego

2024

ALD

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We report a new thermal atomic layer deposition (thermal-ALD) process including an air exposure as a third precursor to deposit crystalline TiO2 anatase thin films from tetrakis(dimethylamido)titanium(IV) (TDMAT) and water at deposition temperatures as low as 180 °C and film thicknesses as low as 10 nm. This ALD process enables TiO2-antase crystal growth during the deposition at low temperatures (< 220 °C). This additional oxidant pulse is used to fully oxidize the Ti to a 4+ state in the amorphous film, lowering the barrier to crystalline anatase formation. This new approach is informed by preliminary studies of post-deposition annealing (PDA) of thermal ALD films in both nitrogen and air atmospheres, which demonstrate the importance of having an oxidizing atmosphere to achieve the nucleation of the crystalline anatase phase. This oxidizing atmosphere is subsequently introduced into the ALD cycle as a third precursor and is shown to be more effective and efficient in promoting the crystalline transformation than even by post-deposition annealing. The crystalline anatase phase is verified by Raman spectroscopy and grazing incidence X-ray diffraction (GIXRD). The mechanism for crystallization during the TDMAT/H2O/air ALD cycle is probed by chemical state analysis via X-ray photoelectron spectroscopy (XPS). We propose that sub-oxidation in TiO2 thin films deposited by the thermal-ALD process inhibits crystallization during ALD from TDMAT/H2O chemistry. Scanning electron microscopy (SEM) is used to investigate the microstructure of these TiO2 thin films as a function of thickness (5 nm to 50 nm) and deposition temperature (180 °C to 220 °C). The reported layer-by-layer air anneal process is found to crystallize entire films in shorter total process times than thermal-ALD with ex situ post deposition annealing at identical temperatures, presumably due to the improved surface diffusion kinetics accessed during the deposition process.

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Section: Tdmat/h 2 O/air Ald Overviewsupporting

confidence: 87%

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing

Wooding,

Kalaitzidou,

Losego

2024

ALD

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“…The main factors affecting the preparation of coatings by the ALD method include the precursor type, cycle time, and reaction temperature. 93 Heterojunction coatings prepared by the ALD method have demonstrated enhanced photoelectrochemical performance. 94 Wang et al 95 results demonstrated the excellent stability of the prepared coating, which can be attributed to the TiO 2 coating formed by the ALD method.…”

Section: Silar Methodmentioning

confidence: 99%

“…The ALD method enables the production of uniform and ultrathin coatings that conform to diverse substrate shapes without modifying their characteristics. The main factors affecting the preparation of coatings by the ALD method include the precursor type, cycle time, and reaction temperature . Heterojunction coatings prepared by the ALD method have demonstrated enhanced photoelectrochemical performance .…”

Section: Synthesis Methods Of Tio2-based Heterojunction Coatingmentioning

confidence: 99%

Review of TiO₂-Based Heterojunction Coatings in Photocathodic Protection

Xu,

Li,

Wen

et al. 2024

ACS Appl. Nano Mater.

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Photocathodic protection coating is an emerging anticorrosion technology that combines the protective characteristics of coating and cathodic protection. TiO 2 is stable and easy to prepare; however, it suffers from a low sunlight utilization rate and low photoelectric conversion efficiency. The construction of TiO 2 -based heterojunction coatings provides an effective solution to these challenges. This work summarizes the synthesis methods of TiO 2based heterojunction coatings, explores the charge-transfer mechanisms associated with various types of heterojunction coatings (e.g., type II heterojunction, p−n junction, Schottky junction, and Z-scheme heterojunction), and reviews the characterization methods used for heterojunction analysis. Finally, the application prospects and future research directions of TiO 2 -based heterojunction coatings are proposed. This study will help researchers understand the fabrication process and application of TiO 2 -based heterojunction coatings in photocathodic protection.

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Synthesis of titanium dioxide thin films via thermo- and plasma-enhanced atomic layer deposition

Ambartsumov,

Chapura,

Tarala

2024

Applied Surface Science

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A systematical investigation of layer growth rate, impurity level and morphology evolution in TiO2 thin films grown by ALD between 100 and 300 °C

Cited by 6 publications

References 58 publications

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing

Review of TiO₂-Based Heterojunction Coatings in Photocathodic Protection

Synthesis of titanium dioxide thin films via thermo- and plasma-enhanced atomic layer deposition

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A systematical investigation of layer growth rate, impurity level and morphology evolution in TiO2 thin films grown by ALD between 100 and 300 °C

Cited by 6 publications

References 58 publications

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing

Review of TiO2-Based Heterojunction Coatings in Photocathodic Protection

Synthesis of titanium dioxide thin films via thermo- and plasma-enhanced atomic layer deposition

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Review of TiO₂-Based Heterojunction Coatings in Photocathodic Protection