Low Temperature Epitaxial Growth of High Permittivity Rutile TiO[sub 2] on SnO[sub 2]

Wang, Hongtao; Xu, Sheng; Gordon, Roy G.

doi:10.1149/1.3457485

Cited by 23 publications

(26 citation statements)

References 22 publications

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“…It is worth noting that, in Refs. [547] and [543] the rutile structure was obtained at temperatures as low as 250 o C, which is a marked improvement in comparison to the case of lattice-mismatched substrates. At high temperatures the TiO2 II structure (mixed with the anatase/rutile structures) can form on sapphire surfaces with certain orientations [206,343].…”

Section: Crystal Structurementioning

confidence: 85%

Titanium dioxide thin films by atomic layer deposition: a review

Niemelä

Marín

Karppinen

2017

Semicond. Sci. Technol.

145

116

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Within its rich phase diagram titanium dioxide is a truly multifunctional material with a property palette that has been shown to span from dielectric to transparent-conducting characteristics, in addition to the well-known catalytic properties. At the same time down-scaling of microelectronic devices has led to an explosive growth in research on atomic layer deposition (ALD) of a wide variety of frontier thin-film materials, among which TiO2 is one of the most popular ones. In this topical review we summarize the advances in research of ALD of titanium dioxide starting from the chemistries of the over 50 different deposition routes developed for TiO2 and the resultant structural characteristics of the films. We then continue with the doped ALD-TiO2 thin films from the perspective of dielectric, transparent-conductor and photocatalytic applications. Moreover, in order to cov er the lat est tr ends in t he research f ield, both the var iously constr ucted TiO2 nanostructures enabled by ALD and the Ti-based hybrid inorganic-organic films grown by the emerging ALD/MLD (combined atomic/molecular layer deposition) technique are discussed.

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Section: Crystal Structurementioning

confidence: 85%

Titanium dioxide thin films by atomic layer deposition: a review

Niemelä

Marín

Karppinen

2017

Semicond. Sci. Technol.

145

116

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“…There are reports in the literature of high‐temperature deposition processes producing rutile TiO 2 films instead of anatase on SnO 2 substrates, although the growth of rutile TiO 2 nanorods/nanowires or branched nanocrystals on SnO 2 is more common. Given that rutile TiO 2 was found in some studies to epitaxially grow on rutile SnO 2 with the substrate [100] aligned with the film [100], the rutile TiO 2 lattice parameter a = 4.594 Å is close enough to the rutile SnO 2 lattice parameter a = 4.737 Å for epitaxial growth without too much lattice strain. TiO 2 ALD processes have been previously shown to produce rutile TiO 2 below 600 °C by substrate templating effects .…”

Section: Resultsmentioning

confidence: 99%

Impact of Conformality and Crystallinity for Ultrathin 4 nm Compact TiO₂ Layers in Perovskite Solar Cells

Roelofs

Pool

Bobb-Semple

et al. 2016

Adv Materials Inter

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The rapid rise in power conversion efficiencies of lead-based perovskite solar cells (PSCs) has established their promise, motivating scale-up and commercialization. As a thin film solar cell, interfacial properties are key to the performance of PSCs; there is a need to further understand which properties are critical to control. In this work, the impact of the compact TiO 2 (com-TiO 2 ) film properties on the performance of mesoporous PSCs is studied. Com-TiO 2 layers are fabricated by spray pyrolysis as well as by atomic layer deposition (ALD), using ALD as a proof-of-concept method to achieve highly conformal films of precisely controlled thickness. The com-TiO 2 layers' conformality and surface roughness are examined by microscopy techniques; their relative crystallinity is studied by grazing-incidence X-ray diffraction with a synchrotron source and an in situ annealing chamber; and completed devices are analyzed by J-V and impedance spectroscopy techniques. The results show that an ultraconformal com-TiO 2 layer can be thinned to 4 nm and match the performance of a ≈50 nm spray-pyrolysis TiO 2 layer. This work concludes that film conformality is the primary consideration for creating a high-performing com-TiO 2 layer, overriding any effects of film crystallinity-a finding that can guide fabrication choices for the scale-up of PSCs.

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“…For example, we reported the formation of the anatase phase on ITO NWs using the same process, 9 while other groups observed rutile phase on rutile substrates with similar lattice parameters, such as SnO 2 and RuO 2 , as the nucleation of the rutile phase can be more energetically stable than that of the anatase phase. [38][39][40][41] Interestingly, the fast Fourier transformed (FFT) patterns show exact matches in crystal directions of the TiO 2 nanoshell and the SnO 2 core. The HRTEM lattice image obtained from the TiO 2 /SnO 2 interface (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…For example, we reported the formation of the anatase phase on ITO NWs using the same process, 9 while other groups observed rutile phase on rutile substrates with similar lattice parameters, such as SnO 2 and RuO 2 , as the nucleation of the rutile phase can be more energetically stable than that of the anatase phase. [38][39][40][41] Table 1; statistical data are shown in Figure S1, ESI †. The 1D-ETL cells' device characteristics differ significantly from those of the mp-ETL cells, although both types exhibit similar PCE.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial 1D electron transport layers for high-performance perovskite solar cells

et al. 2015

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We demonstrate high-performance perovskite solar cells with excellent electron transport properties using a one-dimensional (1D) electron transport layer (ETL). The 1D array-based ETL is comprised of 1D SnO2 nanowires (NWs) array grown on a F:SnO2 transparent conducting oxide substrate and rutile TiO2 nanoshells epitaxially grown on the surface of the 1D SnO2 NWs. The optimized devices show more than 95% internal quantum yield at 750 nm, and a power conversion efficiency (PCE) of 14.2%. The high quantum yield is attributed to dramatically enhanced electron transport in the epitaxial TiO2 layer, compared to that in conventional nanoparticle-based mesoporous TiO2 (mp-TiO2) layers. In addition, the open space in the 1D array-based ETL increases the prevalence of uniform TiO2/perovskite junctions, leading to reproducible device performance with a high fill factor. This work offers a method to achieve reproducible, high-efficiency perovskite solar cells with high-speed electron transport.

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Low Temperature Epitaxial Growth of High Permittivity Rutile TiO[sub 2] on SnO[sub 2]

Cited by 23 publications

References 22 publications

Titanium dioxide thin films by atomic layer deposition: a review

Titanium dioxide thin films by atomic layer deposition: a review

Impact of Conformality and Crystallinity for Ultrathin 4 nm Compact TiO₂ Layers in Perovskite Solar Cells

Epitaxial 1D electron transport layers for high-performance perovskite solar cells

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Low Temperature Epitaxial Growth of High Permittivity Rutile TiO[sub 2] on SnO[sub 2]

Cited by 23 publications

References 22 publications

Titanium dioxide thin films by atomic layer deposition: a review

Titanium dioxide thin films by atomic layer deposition: a review

Impact of Conformality and Crystallinity for Ultrathin 4 nm Compact TiO2 Layers in Perovskite Solar Cells

Epitaxial 1D electron transport layers for high-performance perovskite solar cells

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Impact of Conformality and Crystallinity for Ultrathin 4 nm Compact TiO₂ Layers in Perovskite Solar Cells