How to ‘train’ your CVD to grow large-area 2D materials

Narayanan, Vrinda; Gokul, M. A.; Rahman, Atikur

doi:10.1088/2053-1591/ab5383

Cited by 13 publications

(14 citation statements)

References 65 publications

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“…26 The freshly etched silicon surface was then dipped in a 1% hydrofluoric acid (HF) aqueous solution to obtain a dangling bond-free hydrogen-terminated silicon surface. 27 CVD-grown 28,29 monolayer MoS 2 was transferred to this patterned substrate using polystyrene-assisted wet transfer method. 30 5 nm/65 nm Cr/Au deposited on MoS 2 by thermal vapor deposition served as one of the electrodes for electrical measurements, while the second electrode was taken from the back side of silicon using silver paint.…”

Section: Methodsmentioning

confidence: 99%

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Anilkumar

Rajput

et al. 2022

ACS Appl. Electron. Mater.

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Heterostructures based on two-dimensional (2D) materials have demonstrated huge potential in various modern-day electronic and optoelectronic devices, but their optoelectronic properties are strongly influenced by the defects present in these materials. Hence, an in-depth understanding of the role of defects is vital in designing high-performance optoelectronic devices. Here, we investigated the role of defects in the electronic transport and photoresponse properties of a silicon−MoS 2 p−n junction heterostructure through temperature-dependent electrical studies and demonstrated a method for improving their photoresponse. The presence of space-charge-limited transport with exponentially distributed trap states was evident from the temperature-dependent I−V characteristics. The temperature dependence of the ideality factor and intensity-dependent photoresponse also elucidated the nature of defects. The amplitude of low-frequency 1/f noise was observed to decrease with an increase in temperature, revealing the significant influence of defects on the charge transport. These defects can often cause recombinations, diminishing the photoresponse and severely degrading the optoelectronic properties. A significant enhancement in photoresponse by reducing the recombination centers was obtained by altering the surrounding dielectric environment. For a particular dielectric, the enhancement was observed to be more prominent toward low temperatures. In addition, the surrounding dielectric also effectively suppressed the low-frequency noise levels in the heterostructure. Insights from this study would help in designing and improving the properties of low-dimensional optoelectronic devices.

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Section: Methodsmentioning

confidence: 99%

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Anilkumar

Rajput

et al. 2022

ACS Appl. Electron. Mater.

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“…Narayanan et al. optimized the various parameters for controlling the CVD growth of TMDs, such as the temperature, carrier gas flow rate, and the position of the substrate, using MoS 2 as a model system ( Narayanan et al., 2019 ). The experimental setup consisted of MoO 3 powder in an alumina boat and sulfur powder in a boat present upstream from the MoO 3 boat at a fixed distance.…”

Section: Modeling Of Tmd Cvd Growthmentioning

confidence: 99%

“…This aspect may be examined in the future from a computational perspective, by investigating if aqueous salt solutions can increase the nucleation rate of 2D materials. The authors suggested a sequence of steps to optimize CVD growth processes – first, an ample quantity of precursors should be used to determine the appropriate temperature; subsequently, the position of the substrates/boats should be optimized for different flow rates, at the optimal temperature ( Narayanan et al., 2019 ). The effect of such parameters should also be examined in modeling and simulation efforts.…”

Section: Modeling Of Tmd Cvd Growthmentioning

confidence: 99%

“…Among TMDs, the prominent examples of materials obtained via CVD are molybdenum disulfide (MoS 2 ) and tungsten diselenide (WSe 2 ). Nevertheless, CVD methods are challenging to reproduce, with variability existing between batches grown in different reactors using the same growth conditions ( Narayanan et al., 2019 ). Further, it is quite difficult to optimize the reaction conditions, such as the temperature, pressure, carrier gas flow rate, and vapor-phase composition required for the synthesis of large-area materials with the desired density of defects.…”

Section: Introductionmentioning

confidence: 99%

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Chemical vapor deposition of 2D materials: A review of modeling, simulation, and machine learning studies

Bhowmik¹,

Rajan²

2022

iScience

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“…[23][24][25] Meanwhile, the alkali metal halide-assisted CVD methods enable the rapid fabrication of the continuous and waferscale uniform monolayer TMDs directly on several oxide substrates. [26][27][28][29][30][31][32][33][34] Alkali metal cations promote a rapid increase of the single domain size of monolayer TMDs due to dehydration and nucleation suppression, regardless of the halide anions. [28,31,34] However, excess amounts of alkali metals destroy the crystallinity of monolayer TMDs.…”

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confidence: 99%

Interface Defect Engineering of a Large‐Scale CVD‐Grown MoS₂ Monolayer via Residual Sodium at the SiO₂/Si Substrate

Han

Yun

Woo

et al. 2021

Adv Materials Inter

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In particular, extensive efforts regarding chemical vapor deposition (CVD) methods resulted in a large-scale MoS 2 monolayer of high quality for practical applications. [7][8][9][10][11][12] However, despite the large on-off ratio and high mobility, [3,9] 2D field-effect transistors (FET) composed of monolayer MoS 2 have become burdened with electrical contact issues such as Fermi level pinning (FLP) and high contact resistances. [13][14][15][16][17] The simplest and most abundant mono-sulfur vacancy (V S ) defects in the monolayer MoS 2 cause strong FLP at metal electrodes, which generally induce n-type semiconductor behavior. [18][19][20][21][22] Thus, many methods, which include substitution, charge transfer, intercalation, and electrostatic doping, have been developed to improve the contact properties or modulate the polarity of transition metal dichalcogenides (TMDs). [23][24][25] Meanwhile, the alkali metal halide-assisted CVD methods enable the rapid fabrication of the continuous and waferscale uniform monolayer TMDs directly on several oxide substrates. [26][27][28][29][30][31][32][33][34] Alkali metal cations promote a rapid increase of the single domain size of monolayer TMDs due to dehydration and nucleation suppression, regardless of the halide anions. [28,31,34] However, excess amounts of alkali metals destroy the crystallinity of monolayer TMDs. [29] On the other hand, back-gated FETs based on the MoS 2 monolayers directly grown this way or transferred onto the SiO 2 /Si substrates, used in current Si processing techniques to manufacture electronic devices, [19] showed comparable electrical performances to those fabricated without using alkali metal halides. [8,9,27,34] Nevertheless, such FETs also exhibited n-type behavior. [27,34] Na impurities are notoriously prone to contaminating the SiO 2 surface. [36] Alkali Na metals readily absorb at the oxide substrates during the CVD growth process of monolayer TMDs. [28,29] Furthermore, Na's incorporation at the SiO 2 surface of siloxane or silanol releases electrons into the monolayer MoS 2 conduction band; [37] whereas, in graphene deposited on SiO 2 , Na produces holes. [38] To understand the effect of trapped Na cations, we synthesized the large-scale uniform MoS 2 monolayers on the SiO 2 / Si substrates using NaCl catalysts [27] and then performed two-probe I-V measurements by the forward and reverse bias sweeping between ±30 V in the ambient air condition at room temperature (see Figures S1-S3, Supporting Information). Notably, initial low or negligible source/drain I-V signals in the µA range enhanced to the mA range after the Alkali metal halide-assisted chemical vapor deposition (CVD) methods can produce wafer-scale uniform monolayer transition metal dichalcogenides (TMDs). Further defect engineering is necessary to obtain high-performance functional devices. While defect engineering has focused on the surface of the monolayer TMDs or the contact property, interface defect engineering is rare and non-trivial. Based on a NaCl-assisted CVD-grown l...

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How to ‘train’ your CVD to grow large-area 2D materials

Cited by 13 publications

References 65 publications

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Chemical vapor deposition of 2D materials: A review of modeling, simulation, and machine learning studies

Interface Defect Engineering of a Large‐Scale CVD‐Grown MoS₂ Monolayer via Residual Sodium at the SiO₂/Si Substrate

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How to ‘train’ your CVD to grow large-area 2D materials

Cited by 13 publications

References 65 publications

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS2 Mixed-Dimensional Van der Waals Heterostructure

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS2 Mixed-Dimensional Van der Waals Heterostructure

Chemical vapor deposition of 2D materials: A review of modeling, simulation, and machine learning studies

Interface Defect Engineering of a Large‐Scale CVD‐Grown MoS2 Monolayer via Residual Sodium at the SiO2/Si Substrate

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Product

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Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Interface Defect Engineering of a Large‐Scale CVD‐Grown MoS₂ Monolayer via Residual Sodium at the SiO₂/Si Substrate