ALD-grown two-dimensional TiSx metal contacts for MoS2 field-effect transistors

Mahlouji, Reyhaneh; Kessels, W.M.M.; Sagade, Abhay A.; Bol, Ageeth A.

doi:10.1039/d3na00387f

Cited by 2 publications

(3 citation statements)

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“…In a previous study, a TiS x was used as an interlayer between Au and MoS 2 channel, to improve contact properties of MoS 2 FET. Although the estimated SBH was increased after TiS x deposition, a thin interlayer of 1.2 nm TiS x was observed to reduce R c . It suggested the formation of metal–insulator–semiconductor contacts, rather than the exploitation of semimetallic properties.…”

Section: Introductionmentioning

confidence: 94%

“…Although the estimated SBH was increased after TiS x deposition, a thin interlayer of 1.2 nm TiS x was observed to reduce R c . 32 It suggested the formation of metal−insulator−semiconductor contacts, rather than the exploitation of semimetallic properties. This improvement in I ds caused by reduction of R c was explained by the formation of a flat and clean interface with MoS 2 and the doping effect.…”

Section: T H Imentioning

confidence: 99%

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Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS₂/MoS₂ Heterojunctions

Yoon,

Lee,

Seo

et al. 2024

ACS Appl. Mater. Interfaces

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Two-dimensional transition metal dichalcogenides (2D TMDCs) are considered promising alternatives to Si as channel materials because of the possibility of retaining their superior electronic transport properties even at atomic body thicknesses. However, the realization of high-performance 2D TMDC field-effect transistors remains a challenge owing to Fermilevel pinning (FLP) caused by gap states and the inherent high Schottky barrier height (SBH) within the metal contact and channel layer. This study demonstrates that high-quality van der Waals (vdW) heterojunction-based contacts can be formed by depositing semimetallic TiS 2 onto monolayer (ML) MoS 2 . After confirming the successful formation of a TiS 2 /ML MoS 2 heterojunction, the contact properties of vdW semimetal TiS 2 were thoroughly investigated. With clean interfaces of the TiS 2 /ML MoS 2 heterojunctions, atomic-layer-deposited TiS 2 can induce gap-state saturation and suppress FLP. Consequently, compared with conventional evaporated metal electrodes, the TiS 2 /ML MoS 2 heterojunctions exhibit a lower SBH of 8.54 meV and better contact properties. This, in turn, substantially improves the overall performance of the device, including its on-current, subthreshold swing, and threshold voltage. Furthermore, we believe that our proposed strategy for vdW-based contact formation will contribute to the development of 2D materials used in next-generation electronics.

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Section: Introductionmentioning

confidence: 94%

Section: T H Imentioning

confidence: 99%

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS₂/MoS₂ Heterojunctions

Yoon,

Lee,

Seo

et al. 2024

ACS Appl. Mater. Interfaces

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show abstract

“…TCAD simulations were performed on Silvaco using Athena and Atlas tools. 11 The device simulation parameters are selected such that they match with the experimental data, viz., thickness, lengths, widths, and work functions, etc. The standard Poisson charge transport equations were solved by using the Newton method.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Selective Operation of Enhancement and Depletion Modes of Nanoscale Field-Effect Transistors

Sagade

2024

ACS Appl. Electron. Mater.

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Most of the CMOS field-effect transistors (FETs) are in enhancement mode, absence of charge carriers in the channel at zero gate voltage, to reduce power consumption. In principle, depletion mode transistors have higher currents than the enhancement mode due to ample charge carrier density. For high-frequency applications, the off-state of FET is not a mandatory requirement. Rather the presence of a channel at zero gate bias and sufficiently large saturation mobility is advantageous. Here, we demonstrate that by selecting a particular work function for a gate metal, threshold voltages of the FETs can be changed from negative to positive values that is selective switching between enhancement mode and depletion mode of the operation. The devices are fabricated with Al, Si, and Au gate metals with Au source–drain metal. Well-known p-type molecular semiconductor dinaphthothienothiophene (DNTT) is deposited by evaporation under high vacuum. It is observed that depending on the low- or high-work functions of the gate metal, the channel is absent or present at zero gate voltage. For work functions below and above 4.8 eV, the FET is in enhancement and depletion modes, respectively. We also show that this effect can be strongly observed for thin dielectrics. The experimental results are complemented by TCAD device simulations. This work will be crucial for high-frequency and precision logic-gate applications of organic as well as 2D materials devices.

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ALD-grown two-dimensional TiS_x metal contacts for MoS₂ field-effect transistors

Abstract: 2D metallic TiSx can be grown at low temperatures using atomic layer deposition (ALD). Herein, we show that ultrathin films of 2D TiSx (∼1.2 nm) prepared by ALD can be used as contacts to 2D MoS2 in field-effect transistors (FETs) and improve the overall device metrics.

Cited by 2 publications

References 80 publications

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS₂/MoS₂ Heterojunctions

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS₂/MoS₂ Heterojunctions

Selective Operation of Enhancement and Depletion Modes of Nanoscale Field-Effect Transistors

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ALD-grown two-dimensional TiSx metal contacts for MoS2 field-effect transistors

Abstract: 2D metallic TiSx can be grown at low temperatures using atomic layer deposition (ALD). Herein, we show that ultrathin films of 2D TiSx (∼1.2 nm) prepared by ALD can be used as contacts to 2D MoS2 in field-effect transistors (FETs) and improve the overall device metrics.

Cited by 2 publications

References 80 publications

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS2/MoS2 Heterojunctions

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS2/MoS2 Heterojunctions

Selective Operation of Enhancement and Depletion Modes of Nanoscale Field-Effect Transistors

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Product

Resources

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ALD-grown two-dimensional TiS_x metal contacts for MoS₂ field-effect transistors

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS₂/MoS₂ Heterojunctions

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS₂/MoS₂ Heterojunctions