Evaluation of border traps and interface traps in HfO
                    <sub>2</sub>
                    /MoS
                    <sub>2</sub>
                    gate stacks by capacitance–voltage analysis

Zhao, Peng; Khosravi, Ava; Azcatl, Angelica; Bolshakov, Pavel; Mirabelli, Gioele; Caruso, Enrico; Hinkle, Christopher L.; Hurley, Paul K.; Wallace, Robert M.; Young, C.D.

doi:10.1088/2053-1583/aab728

Cited by 78 publications

(69 citation statements)

References 32 publications

(48 reference statements)

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“…On the other hand, the top high‐ k oxide is typically formed on the inert MoS 2 surface by atomic layer deposition (ALD) at a relatively low temperature with the aid of a buffer layer, which may introduce many traps inside. The traps close to the interface serve as quick traps while the traps inside the oxide serve as slow traps, as discussed in several reports . Third, trap (III) represents the strain in MoS 2 induced externally.…”

Section: Introductionmentioning

confidence: 94%

“…Here, the recent demonstration of a natural thin‐body MoS 2 FET with an effective channel length of ≈ 3.9 nm has facilitated research on 2D layered channels due to overcoming the scaling limit of ≈ 5 nm for Si gate length . Although the dangling‐bond‐free surface of the layered channel is expected to ideally provide an electrically inert interface, there are many reports on the wide range of interface state densities ( D it ) from 10 11 to 10 13 eV −1 cm −2 for high‐ k top‐gate n ‐MoS 2 FET in reality, which must be reduced to improve the device performance. To date, several physical origins for D it have been proposed, which are summarized in Figure a.…”

Section: Introductionmentioning

confidence: 99%

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Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS₂ Field‐Effect Transistors

Fang

Toyoda

Taniguchi

et al. 2019

Adv Funct Materials

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2D materials are promising to overcome the scaling limit of Si field-effect transistors (FETs). However, the insulator/2D channel interface severely degrades the performance of 2D FETs, and the origin of the degradation remains largely unexplored. Here, the full energy spectra of the interface state densities (D it ) are presented for both n-and p-MoS 2 FETs, based on the comprehensive and systematic studies, i.e., full rage of channel thickness and various gate stack structures with h-BN as well as high-k oxides. For n-MoS 2 , D it around the mid-gap is drastically reduced to 5 × 10 11 cm −2 eV −1 for the heterostructure FET with h-BN from 5 × 10 12 cm −2 eV −1 for the high-k top-gate. On the other hand, D it remains high, ≈10 13 cm −2 eV −1 , even for the heterostructure FET for p-MoS 2 . The systematic study elucidates that the strain induced externally through the substrate surface roughness and high-k deposition process is the origin for the interface degradation on conduction band side, while sulfur-vacancy-induced defect states dominate the interface degradation on valance band side. The present understanding of the interface properties provides the key to further improving the performance of 2D FETs.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS₂ Field‐Effect Transistors

Fang

Toyoda

Taniguchi

et al. 2019

Adv Funct Materials

View full text Add to dashboard Cite

show abstract

“…[77][78][79][80][81][82][83][84][85] By exploiting the O 3 surface functionalization approach for high-j dielectric ALD, Zhao et al demonstrated the ability to employ electrical characterization test structures incorporating a more conventional top gate geometry, thereby enabling an inroad to understanding the impact of defects at the high-j/MoS 2 interface as well as those associated with the high-j itself through impedance spectroscopy. 77,80,84 Figure 10 presents the transistor test structure schematic and the associated TEM cross section of a top gate device stack achieved after HfO 2 ALD enabled by O 3 -functionalization. It is seen that the physical characterization reveals a uniform HfO 2 deposition on the 7-layer exfoliated and transferred MoS 2 layer on SiO 2 .…”

Section: Device Characterization Of Uv-ozone Functionalized Mosmentioning

confidence: 99%

“…The impact of annealing in N 2 and forming gas (N 2 :H 2 ) has also been studied to better optimize the device response, 82 as well as the detailed extraction methods for interface defect traps and nearby (border) defect traps in the HfO 2 using these structures. 84 The details of the device test structure and the electrical characterization and property extraction (e.g., D it ) remain a contemporary research topic in the community. Interface state density for HfO 2 /MoS 2 / SiO 2 /Si on the order of 10 13 /cm 2 eV as well as the presence of significant border traps in the high-j dielectric has been reported.…”

Section: Device Characterization Of Uv-ozone Functionalized Mosmentioning

confidence: 99%

“…Interface state density for HfO 2 /MoS 2 / SiO 2 /Si on the order of 10 13 /cm 2 eV as well as the presence of significant border traps in the high-j dielectric has been reported. 80,84 Recent work demonstrated the impact of the choice of the back-gate dielectric (Al 2 O 3 versus HfO 2 ) on the extracted D it ($ 10 11 /cm 2 eV), the concomitant improvement in the measured sub-threshold slope ($ 69 mV/dec for Al 2 O 3 ), and mobility of the associated transistors ($ 145 cm 2 /Vs). 81,83,85 Preliminary studies on the impact of 400°C forming gas anneals on HfO 2 /MoS 2 transistors showed a decrease in the threshold voltage, decrease in leakage current, and minimized I-V hysteresis.…”

Section: Device Characterization Of Uv-ozone Functionalized Mosmentioning

confidence: 99%

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UV-Ozone Functionalization of 2D Materials

McDonnell

Wallace

2018

JOM

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Integrating two-dimensional (2D) materials into the current nanoelectronic process requires control over the deposition of gate oxides onto these materials. Atomic layer deposition (ALD) relies on surface dangling bonds that are scarce for 2D materials. This review summarizes the advances made in understanding and controlling the nucleation of ALD oxides on these materials. As an example, we focus on ozone-based processes including UV-ozone pretreatments, which we have found to effectively functionalize the surface of molybdenum disulfide. Furthermore, we discuss the advantages and limitations of various functionalization or seeding techniques, such as limits in scalability or damage to the 2D materials. Atomic Layer DepositionAtomic layer deposition (ALD) is now a standard industry tool for the deposition of ultra-thin films, and the mechanisms have been covered in a review by S. George. 25 Briefly, ALD works by sequentially exposing a surface to precursor species that can react with the surface to form self-limiting monolayers, which is shown schematically in Fig.

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Charge Carrier Mobility and Series Resistance Extraction in 2D Field‐Effect Transistors: Toward the Universal Technique

Chien

Feng

Chen

et al. 2021

Adv Funct Materials

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2D semiconductor field-effect transistors (2D FETs) have emerged as a promising candidate for beyond-silicon electronics applications. However, its device performance has often been limited by the metal-2D semiconductor contact, and the non-negligible contact resistance (R SD ) not only deteriorates the on-state current but also hinders the direct characterization of the intrinsic properties of 2D semiconductors (e.g., intrinsic charge carrier mobility, μ int ). Therefore, a proper extraction technique that can independently characterize the metal-2D semiconductor contact behavior and the intrinsic properties of a 2D semiconducting layer is highly desired. In this study, a universal yet simple method is developed to accurately extract the critical parameters in 2D FETs, including characteristic temperature (T o ), threshold voltage (V T ), R SD , and μ int . The practicability of this method is extensively explored by characterizing the temperature-dependent carrier transport behavior and the strain-induced band structure modification in 2D semiconductors. Technology computer aided design simulation is subsequently employed to verify the precision of R SD extraction. Furthermore, the universality of the proposed method is validated by successfully implementing the extraction to various 2D semiconductors, including black phosphorus, indium selenide, molybdenum disulfide, rhenium disulfide, and tungsten disulfide with top-and bottomgated configurations.

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Evaluation of border traps and interface traps in HfO ₂ /MoS ₂ gate stacks by capacitance–voltage analysis

Cited by 78 publications

References 32 publications

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS₂ Field‐Effect Transistors

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS₂ Field‐Effect Transistors

UV-Ozone Functionalization of 2D Materials

Charge Carrier Mobility and Series Resistance Extraction in 2D Field‐Effect Transistors: Toward the Universal Technique

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Evaluation of border traps and interface traps in HfO 2 /MoS 2 gate stacks by capacitance–voltage analysis

Cited by 78 publications

References 32 publications

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS2 Field‐Effect Transistors

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS2 Field‐Effect Transistors

UV-Ozone Functionalization of 2D Materials

Charge Carrier Mobility and Series Resistance Extraction in 2D Field‐Effect Transistors: Toward the Universal Technique

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Product

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Evaluation of border traps and interface traps in HfO ₂ /MoS ₂ gate stacks by capacitance–voltage analysis

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS₂ Field‐Effect Transistors

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS₂ Field‐Effect Transistors