Semiconducting TiO2−xSx thin films by atomic layer deposition of TiS2 and its oxidation in ambient

Nam, Hochul; Yang, Han-Chul; Kim, Eun-Soo; Bae, Changdeuck; Shin, Hyunjung

doi:10.1116/1.5079583

Cited by 13 publications

(22 citation statements)

References 36 publications

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“…Previously, TiS 2 has been reported to be synthesized by ALD using TiCl 4 and H 2 S with a growth per cycle (GPC) between 0.15 and 0.5 Å depending on the deposition temperature. 16,17 Recently, ALD of amorphous TiS 2 has been reported by Nam et al 18 using tetrakis(dimethylamido)titanium and H 2 S at a deposition temperature between 120 and 180 °C with a GPC of ∼0.5 Å. They also reported the surface oxidation of TiS 2 after exposure to the ambient conditions.…”

Section: Introductionmentioning

confidence: 92%

“…Titanium sulfide (TiS x ) is one of the systems that could provide an excellent framework for phase control during synthesis. TiS 2 has been studied extensively for batteries, optics, and thermoelectric material applications and has been synthesized by various techniques such as chemical vapor transport (CVT), chemical vapor deposition (CVD), − atomic layer deposition (ALD), − and wet chemical synthesis . Interestingly, the electrical properties of TiS 2 have been under debate for the last few decades, with hypotheses from both theory and experimental results splitting between a semiconducting, metallic, or semimetallic nature. , Recently, TiS 2 has been considered as a degenerate, small-gap semiconductor or a semimetal owing to its high conductivity and optical absorption properties .…”

Section: Introductionmentioning

confidence: 99%

“…The ALD method has advantages such as precise thickness control and conformal growth over a large area. , In addition, most ALD processes are performed at low temperatures (<450 °C), which are favorable for device manufacturing schemes. − Recently, interest in controlling the phase as well as the composition of metal-oxide-based materials has been made viable by ALD. − Therefore, ALD could serve as an ideal technique for synthesizing both TMDCs and TMTCs over a large area at low temperature with precise thickness control. Previously, TiS 2 has been reported to be synthesized by ALD using TiCl 4 and H 2 S with a growth per cycle (GPC) between 0.15 and 0.5 Å depending on the deposition temperature. , Recently, ALD of amorphous TiS 2 has been reported by Nam et al using tetrakis(dimethylamido)titanium and H 2 S at a deposition temperature between 120 and 180 °C with a GPC of ∼0.5 Å. They also reported the surface oxidation of TiS 2 after exposure to the ambient conditions.…”

Section: Introductionmentioning

confidence: 99%

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Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition

et al. 2019

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Phase-controlled synthesis of two-dimensional (2D) transition-metal chalcogenides (TMCs) at low temperatures with a precise thickness control has to date been rarely reported. Here, we report on a process for the phase-controlled synthesis of TiS2 (metallic) and TiS3 (semiconducting) nanolayers by atomic layer deposition (ALD) with precise thickness control. The phase control has been obtained by carefully tuning the deposition temperature and coreactant composition during ALD. In all cases, characteristic self-limiting ALD growth behavior with a growth per cycle (GPC) of ∼0.16 nm per cycle was observed. TiS2 was prepared at 100 °C using H2S gas as coreactant and was also observed using H2S plasma as a coreactant at growth temperatures between 150 and 200 °C. TiS3 was synthesized only at 100 °C using H2S plasma as the coreactant. The S2 species in the H2S plasma, as observed by optical emission spectroscopy, has been speculated to lead to the formation of the TiS3 phase at low temperatures. The control between the synthesis of TiS2 and TiS3 was elucidated by Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution electron microscopy, and Rutherford backscattering study. Electrical transport measurements showed the low resistive nature of ALD grown 2D-TiS2 (1T-phase). Postdeposition annealing of the TiS3 layers at 400 °C in a sulfur-rich atmosphere improved the crystallinity of the film and yielded photoluminescence at ∼0.9 eV, indicating the semiconducting (direct band gap) nature of TiS3. The current study opens up a new ALD-based synthesis route for controlled, scalable growth of transition-metal di- and tri-chalcogenides at low temperatures.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition

et al. 2019

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“…Tens of nm rough films (50 nm) LIB, NIB [255] Ti(NMe 2 ) 4 + H 2 S 150-180 ≈5-100 nm films (amorp., oxidizes) - [256] 100 ≈30 nm rough film (cryst.) - [257] Ti(NMe 2 ) 4 + H 2 S plasma 150-200 ≈30 nm rough film (≈50-100 nm) - [257] WS 2 WCl 6 + H 2 S e) 390 a few-10 ML (cryst.)…”

mentioning

confidence: 99%

Atomic Layer Deposition of 2D Metal Dichalcogenides for Electronics, Catalysis, Energy Storage, and Beyond

Mattinen

Leskelä

Ritala

2021

Adv Materials Inter

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it was soon replaced by other materials. Research on the fundamental properties and preparation of TMDC monolayers in solution (1986), [8] on single-crystal substrates in ultrahigh vacuum (2001), [9] and in an accessible way using mechanical exfoliation [10] (2005) followed. It was the discovery of graphene in 2004 [11] with its ever expanding list of unique and exciting properties, phenomena, and potential applications [12] that amassed broad attention to 2D materials and resulted in the 2010 Nobel Prize in Physics awarded to Andre Geim and Konstantin Novoselov. Tremendous efforts have been put toward synthesis and applications of graphene, including the billion euro Graphene Flagship project funded by the European Union. [13,14] Graphene is a semimetal, however, and the need to have semiconducting materials for many crucial applications, in particular in electronics, has led researchers to search for other 2D materials. The scientific community turned to TMDCs following breakthroughs in observation of unique thickness-dependent properties, [15,16] monolayer synthesis using chemical vapor deposition (CVD), [17,18] and demonstration of high-performance semiconductor devices [19-21] in 2010-2013 (Figure 1). Indeed, in 2013 the number of scientific publications on TMDCs, in particular MoS 2 , nearly tripled over 2012, and the strong growth has continued to date, fueled by advances in synthesis, new devices, and exciting physical phenomena. The explosive growth in MoS 2 research has also expanded to other TMDCs, [22] resulting in yet new phenomena and potential applications being found. [23-26] It is now clear that TMDCs are remarkable in many ways. Their layered crystal structure gives rise to fundamental physics not seen in 3D materials, which enables novel devices and applications. [25,26,32,34-36] The layered structure also gives TMDCs their highly anisotropic properties, extremely high specific surface areas, possibility to intercalate different species between the layers, and stability as ultrathin sheets down to three atomic layers thick. The TMDC family contains dozens of different materials from semiconductors to semimetals, metals, and even superconductors. [5,22,25,34] However, TMDC research is still mostly in the early discovery stages and the investigations of TMDCs largely continue using flakes produced by mechanical exfoliation of bulk crystals. [10,26] Unfortunately, this method cannot be scaled up for practical 2D transition metal dichalcogenides (TMDCs) are among the most exciting materials of today. Their layered crystal structures result in unique and useful electronic, optical, catalytic, and quantum properties. To realize the technological potential of TMDCs, methods depositing uniform films of controlled thickness at low temperatures in a highly controllable, scalable, and repeatable manner are needed. Atomic layer deposition (ALD) is a chemical gas-phase thin film deposition method capable of meeting these challenges. In this review, the applications evaluated for ALD TMDCs are systematically...

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“…Sulfur as a chalcogen element from the same group of the periodic table of elements as oxygen (and as an anion with À2 oxidation state) has been chosen as a dopant of TiO 2 structures by many authors (Umebayashi et al, 2002(Umebayashi et al, , 2003Ni et al, 2016;Nam et al, 2019;Yamamoto et al, 2004). Wang & Lewis (2005) and Chen & Burda (2008) investigated pristine and sulfur-doped anatase and rutile structures and their electronic properties.…”

Section: Introductionmentioning

confidence: 99%

Anion substitution and influence of sulfur on the crystal structures, phase transitions, and electronic properties of mixed TiO₂/TiS₂ compounds

Jovanović¹,

Zagorac²,

Matović³

et al. 2021

Acta Crystallogr B Struct Sci Cryst Eng Mater

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Recent studies of TiO2/TiS2 nanostructures with various morphologies have been reported, usually showing improved properties with applications from electronics and catalysis to solar cells and medicine. However, there is a limited number of studies on the crystal structures of TiO2/TiS2 compounds with corresponding properties. In this research, relevant crystal structures of TiO1–x S x (x = 0, 0.25, 0.5, 0.75 and 1) solid solutions were investigated using an ab initio method. For each composition, crystal structures adopting anatase, rutile and CdI2 structure type were calculated on LDA-PZ and GGA-PBE levels of theory. Novel phase transitions and predicted structures are presented, and apart from several interesting metastable structures, a very interesting pressure-induced phase transition is found in the TiOS compound. Furthermore, electronic properties were studied through the dependence of semiconducting properties on dopant concentration. The first description of the electronic properties of the mixed TiO1–x S x compounds in crystal form has been presented, followed by a detailed study of the structure–property relationship, which will possibly have numerous industrial and technological applications.

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Semiconducting TiO2−xSx thin films by atomic layer deposition of TiS2 and its oxidation in ambient

Cited by 13 publications

References 36 publications

Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition

Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition

Atomic Layer Deposition of 2D Metal Dichalcogenides for Electronics, Catalysis, Energy Storage, and Beyond

Anion substitution and influence of sulfur on the crystal structures, phase transitions, and electronic properties of mixed TiO₂/TiS₂ compounds

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Semiconducting TiO2−xSx thin films by atomic layer deposition of TiS2 and its oxidation in ambient

Cited by 13 publications

References 36 publications

Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition

Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition

Atomic Layer Deposition of 2D Metal Dichalcogenides for Electronics, Catalysis, Energy Storage, and Beyond

Anion substitution and influence of sulfur on the crystal structures, phase transitions, and electronic properties of mixed TiO2/TiS2 compounds

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Anion substitution and influence of sulfur on the crystal structures, phase transitions, and electronic properties of mixed TiO₂/TiS₂ compounds