Impact of surface rouglmess on silicon and germanium ultra-thin-body MOSFETs

Low, Tony; Li, M.F.; Fan, Wenhui; Ng, S. T.; Yeo, Yee-Chia; Zhu, Chunxiang; Chin, Albert; Chan, Lap; Kwong, Dim‐Lee

doi:10.1109/iedm.2004.1419092

Cited by 23 publications

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“…In order to achieve field-effect transistor (FET) gate lengths below 10 nm, transistor channel thicknesses below approximately 2 nm are required to maintain good gate control of the channel and to minimize leakage current. , In such thin films, three-dimensional (3D) semiconductors like Si suffer from surface roughness (SR) effects: SR scattering reduces their mobility by nearly 2 orders of magnitude, − and SR fluctuations (coupled with increases of band gap due to quantization effects) can lead to strong variability in threshold voltage. , In contrast, when sufficiently clean, two-dimensional (2D) materials such as graphene and MoS 2 do not have surface roughness and exhibit good electrical mobility that is largely independent of channel thickness. − MoS 2 , a transition metal dichalcogenide (TMD), is a semiconductor with good mobility (∼100 cm 2 V –1 s –1 in sub-2 nm thick films) and high on/off FET current ratio (∼10 7 ) near room temperature. − Considering the nascent stage of ultra-thin TMD material synthesis and device fabrication, there is great potential for improvement, particularly from the perspective of device transport.…”

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“…1,2 In such thin films, three-dimensional (3D) semiconductors like Si suffer from surface roughness (SR) effects: SR scattering reduces their mobility by nearly 2 orders of magnitude, 3−8 and SR fluctuations (coupled with increases of band gap due to quantization effects 9 ) can lead to strong variability in threshold voltage. 10,11 In contrast, when sufficiently clean, two-dimensional (2D) materials such as graphene and MoS 2 do not have surface roughness and exhibit good electrical mobility that is largely independent of channel thickness. 12−14 MoS 2 , a transition metal dichalcogenide (TMD), is a semiconductor with good mobility (∼100 cm 2 V −1 s −1 in sub-2 nm thick films) and high on/off FET current ratio (∼10 7 ) near room temperature.…”

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Improved Contacts to MoS₂ Transistors by Ultra-High Vacuum Metal Deposition

et al. 2016

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The scaling of transistors to sub-10 nm dimensions is strongly limited by their contact resistance (RC). Here we present a systematic study of scaling MoS2 devices and contacts with varying electrode metals and controlled deposition conditions, over a wide range of temperatures (80 to 500 K), carrier densities (10(12) to 10(13) cm(-2)), and contact dimensions (20 to 500 nm). We uncover that Au deposited in ultra-high vacuum (∼10(-9) Torr) yields three times lower RC than under normal conditions, reaching 740 Ω·μm and specific contact resistivity 3 × 10(-7) Ω·cm(2), stable for over four months. Modeling reveals separate RC contributions from the Schottky barrier and the series access resistance, providing key insights on how to further improve scaling of MoS2 contacts and transistor dimensions. The contact transfer length is ∼35 nm at 300 K, which is verified experimentally using devices with 20 nm contacts and 70 nm contact pitch (CP), equivalent to the "14 nm" technology node.

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Improved Contacts to MoS₂ Transistors by Ultra-High Vacuum Metal Deposition

et al. 2016

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“…20 shows the SR limited hole mobility as a function of body thickness for Si (SOI) and Ge (GOI) channels. The variation of hole mobility is outlined for various surface orientations [19].…”

Section: Fig 17 Electron Mobility In 23-nm Ultra-thin-body Fet Undmentioning

confidence: 99%

Performance and new effects in advanced SOI devices and materials

Jomaah

2005

Microelectronic Engineering

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“…Also, for sub-10-nm field-effect transistors (FETs), effective gate control is needed. Furthermore, Si suffers from surface roughness (SR) effects that can reduce their charge carrier mobility [ 11 ] and lead to strong variability in threshold voltages [ 12 ]. Encouragingly, in recent years, the introduction of high-k gate dielectrics and metal gates has been successful for improving transistor performance [ 13 ].…”

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confidence: 99%

Molecular Adsorption of NH3 and NO2 on Zr and Hf Dichalcogenides (S, Se, Te) Monolayers: A Density Functional Theory Study

2020

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Due to their atomic thicknesses and semiconducting properties, two-dimensional transition metal dichalcogenides (TMDCs) are gaining increasing research interest. Among them, Hf- and Zr-based TMDCs demonstrate the unique advantage that their oxides (HfO2 and ZrO2) are excellent dielectric materials. One possible method to precisely tune the material properties of two-dimensional atomically thin nanomaterials is to adsorb molecules on their surfaces as non-bonded dopants. In the present work, the molecular adsorption of NO2 and NH3 on the two-dimensional trigonal prismatic (1H) and octahedral (1T) phases of Hf and Zr dichalcogenides (S, Se, Te) is studied using dispersion-corrected periodic density functional theory (DFT) calculations. The adsorption configuration, energy, and charge-transfer properties during molecular adsorption are investigated. In addition, the effects of the molecular dopants (NH3 and NO2) on the electronic structure of the materials are studied. It was observed that the adsorbed NH3 donates electrons to the conduction band of the Hf (Zr) dichalcogenides, while NO2 receives electrons from the valance band. Furthermore, the NO2 dopant affects than NH3 significantly. The resulting band structure of the molecularly doped Zr and Hf dichalcogenides are modulated by the molecular adsorbates. This study explores, not only the properties of the two-dimensional 1H and 1T phases of Hf and Zr dichalcogenides (S, Se, Te), but also tunes their electronic properties by adsorbing non-bonded dopants.

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Impact of surface rouglmess on silicon and germanium ultra-thin-body MOSFETs

Cited by 23 publications

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Improved Contacts to MoS₂ Transistors by Ultra-High Vacuum Metal Deposition

Improved Contacts to MoS₂ Transistors by Ultra-High Vacuum Metal Deposition

Performance and new effects in advanced SOI devices and materials

Molecular Adsorption of NH3 and NO2 on Zr and Hf Dichalcogenides (S, Se, Te) Monolayers: A Density Functional Theory Study

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Impact of surface rouglmess on silicon and germanium ultra-thin-body MOSFETs

Cited by 23 publications

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Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal Deposition

Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal Deposition

Performance and new effects in advanced SOI devices and materials

Molecular Adsorption of NH3 and NO2 on Zr and Hf Dichalcogenides (S, Se, Te) Monolayers: A Density Functional Theory Study

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Product

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Improved Contacts to MoS₂ Transistors by Ultra-High Vacuum Metal Deposition

Improved Contacts to MoS₂ Transistors by Ultra-High Vacuum Metal Deposition