Substrate-mediated growth of oriented, vertically aligned MoS2 nanosheets on vicinal and on-axis SiC substrates

Bradford, Jonathan; Zaganelli, Aurora; Qi, Dongchen; Zebardastan, Negar; Shafiei, Mahnaz; MacLeod, Jennifer; Motta, Nunzio

doi:10.1016/j.apsusc.2021.149303

Cited by 15 publications

(7 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the results from the Mo 3d and EXAFS core levels of the amorphous phases are mutually supportive, the S 2p analysis provides the missing information on the sulfur arrangement. Analysis of the S 2p core-level spectra identified three doublets contributions in both amorphous phases, namely S(-II) in the 1T′-like phase (green) with E B (2p 3/2 ) = 161.62 eV, ,− S(-II) in the 2H-like phase (orange) with E B (2p 3/2 ) = 162.24 eV, and S n (-II) with E B (2p 3/2 ) = 162–164 eV assigned to polysulfides with a variable number of sulfur atoms in the chain . At first glance, amorphous MoS 4 contains more S–S bonds than amorphous MoS 2 .…”

Section: Resultsmentioning

confidence: 99%

Improved Ordering of Quasi-Two-Dimensional MoS₂ via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS_2+x

Krbal

Prokop

Přikryl

et al. 2022

Crystal Growth & Design

View full text Add to dashboard Cite

The synthesis of stoichiometric two-dimensional (2D) transition-metal dichalcogenides (TMDC) over large areas remains challenging. Using a combination of X-ray diffraction and X-ray absorption spectroscopy, we demonstrate the advantages of using a thin amorphous layer of S-rich MoS2 (MoS4 in this paper) for the growth of well-ordered crystalline MoS2 films via annealing at 900 °C. In contrast to the crystallization of stoichiometric amorphous MoS2, the crystallization of the as-deposited amorphous MoS4 phase shows the strong preferred ordering of layered MoS2 on a Si/SiO x nontemplating substrate with the dominant (002) crystallographic plane and accompanying Kiessig fringes, which indicate the improved crystallinity of the MoS2 layers. A similar effect can only be achieved by the templated crystallization of an amorphous MoS2 thin film deposited on a c-plane sapphire substrate. We suggest that the crystal growth improvement originates from the lower coordination number (CN) of the Mo atoms in the MoS4 amorphous phase (CN = 4) in comparison with that of amorphous MoS2 (CN = 6) and the gradual release of free sulfur atoms from the thin film during crystallization.

show abstract

Section: Resultsmentioning

confidence: 99%

Improved Ordering of Quasi-Two-Dimensional MoS₂ via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS_2+x

Krbal

Prokop

Přikryl

et al. 2022

Crystal Growth & Design

View full text Add to dashboard Cite

show abstract

“…The higher is the intensity of A 1g , the more is the freedom in out‐of‐plane vibration, which means the MoS 2 is vertically standing. [ 33 ] Here, the A 1g / E 1 2g intensity ratio is 1.9 revealing the existence of standing MoS 2 sheets on MoS 2 /NPG‐280. [ 67 ]…”

Section: Resultsmentioning

confidence: 99%

“…[27] CVD starting from MoO 3 and S precursors can be used to grow high-quality MoS 2 heterostructures on several substrates in a scalable way. [9,[28][29][30][31][32][33] Controlling the size, shape, and number of layers of MoS 2 is possible by changing the growth parameters of the CVD reactor; [34] however, the growth depends critically on the interaction with the substrate and a full understanding of this process is still lacking.…”

Section: Introductionmentioning

confidence: 99%

2D MoS₂ Heterostructures on Epitaxial and Self‐Standing Graphene for Energy Storage: From Growth Mechanism to Application

Zebardastan

Bradford

Gupta

et al. 2021

Adv Materials Technologies

Self Cite

View full text Add to dashboard Cite

Layered molybdenum disulphide (MoS2) crystals in combination with graphene create the opportunity for the development of heterostructures with tailored surface and structural properties for energy storage applications. Herein, 2D heterostructures are developed by growing MoS2 on epitaxial and self‐standing nanoporous graphene (NPG) using chemical vapor deposition (CVD). The effect of substrate as well as different CVD growth parameters such as temperature, amount of sulfur and MoO3 precursors, and argon flow on the growth of MoS2 is systematically investigated. Interestingly, various structures of MoS2 such as monolayer triangular islands, spirals, standing sheets, and irregular stacked multilayered MoS2 are successfully developed. The growth mechanism is proposed using different advanced characterization techniques. The formation of a continuous wetting layer with grain boundaries over the surface prior to formation of any other structures is detected. As a proof of principle, MoS2/NPG is employed for the first time as anode material in potassium ion battery. The electrode delivers a specific capacity of 389 mAh g−1 with over 98% stability after 200 cycles. The porous structures clearly facilitate the ion transport which is beneficial for the ion battery. These encouraging results open new opportunities to develop hierarchical heterostructures of 2D‐materials for next‐generation energy storage technologies.

show abstract

“…[ 17 ] Highly crystalline few layers MoS 2 on 6H‐SiC(0001) have been also obtained by PLD at a substrate temperature of 700 °C. [ 21 ] Furthermore, inhomogeneous MoS 2 flakes with dendritic shape, [ 25 ] or vertically standing triangular MoS 2 domains with respect to the basal planes of 6H‐SiC [ 26 ] and 4H‐SiC [ 27 ] have been obtained by CVD properly tailoring the growth conditions. While vertically standing MoS 2 exposing edges can be interesting for catalysis and hydrogen evolution reaction (HER) applications, [ 27 ] layered MoS 2 films uniformly covering the SiC(0001) basal plane are highly attractive as building blocks of heterojunction devices exploiting vertical current transport at MoS 2 /SiC interfaces.…”

Section: Introductionmentioning

confidence: 99%

“…[ 21 ] Furthermore, inhomogeneous MoS 2 flakes with dendritic shape, [ 25 ] or vertically standing triangular MoS 2 domains with respect to the basal planes of 6H‐SiC [ 26 ] and 4H‐SiC [ 27 ] have been obtained by CVD properly tailoring the growth conditions. While vertically standing MoS 2 exposing edges can be interesting for catalysis and hydrogen evolution reaction (HER) applications, [ 27 ] layered MoS 2 films uniformly covering the SiC(0001) basal plane are highly attractive as building blocks of heterojunction devices exploiting vertical current transport at MoS 2 /SiC interfaces. These can find application both in the state‐of‐the‐art 4H‐SiC technology (Schottky and Junction Barrier Schottky diodes) for energy‐efficient power conversion, [ 28 ] as well as for the implementation of novel device concepts for ultra‐fast switching, including p + ‐MoS 2 /n + ‐SiC Esaki diodes [ 29 ] and vertical hot electron transistors with a n‐MoS 2 base [ 30,31 ] and n + ‐SiC emitter.…”

Section: Introductionmentioning

confidence: 99%

Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS₂ on Ion Implantation Doped 4H‐SiC

Giannazzo

Panasci

Schilirò

et al. 2022

Adv Materials Inter

View full text Add to dashboard Cite

such as the thickness-dependent bandgap, which are attractive for ultra-scaled digital electronics beyond silicon, optoelectronics, and energy applications. [1] The danglingbond free structure of TMDs offers the unique possibility of realizing high-quality van der Waals heterostructures with bulk semiconductors for the implementation of advanced heterojunction devices exploiting current transport at the interface. [2][3][4][5] In particular, the integration of single or few layers MoS 2 with wide bandgap semiconductors, such as the group-III Nitrides (GaN, AlN, and AlGaN alloys) and 4H-SiC, is currently the object of increasing interest in optoelectronics (e.g., for the realization of high responsivity dual-band photo detectors covering the spectral ranges of visible and ultraviolet), [6][7][8][9][10][11] and in electronics (e.g., for the realization of heterojunction diodes, including band-toband tunnel diodes). [12][13][14][15][16][17] Motivated by these interests, different approaches have been employed to fabricate such heterojunction devices, including the transfer of MoS 2 flakes exfoliated from bulk crystals [6,9,10] or grown on foreign substrates, [12,13,18] and the direct deposition of MoS 2 on GaN [14][15][16] or 4H-SiC. [11,17] In particular, nearly unstrained and highly oriented monolayer MoS 2 triangular domains on the GaN( 0001) basal plane have been In this paper, 2D/3D heterojunction diodes have been fabricated by pulsed laser deposition (PLD) of MoS 2 on 4H-SiC(0001) surfaces with different doping levels, i.e., n − epitaxial doping (≈10 16 cm −3 ) and n + ion implantation doping (>10 19 cm −3 ). After assessing the excellent thickness uniformity (≈3L-MoS 2 ) and conformal coverage of the PLD-grown films by Raman mapping and transmission electron microscopy, the current injection across the heterojunctions is investigated by temperature-dependent current-voltage characterization of the diodes and by nanoscale current mapping with conductive atomic force microscopy. A wide tunability of the transport properties is shown by the SiC surface doping, with highly rectifying behavior for the MoS 2 /n − SiC junction and a strongly enhanced current injection for MoS 2 /n + SiC one. Thermionic emission is found the dominant mechanism ruling forward current in MoS 2 /n − SiC diodes, with an effective barrier Φ B = (1.04 ± 0.09) eV. Instead, the significantly lower effective barrier Φ B = (0.31 ± 0.01) eV and a temperature-dependent ideality factor for MoS 2 /n + SiC junctions is explained by thermionic-field-emission through the thin depletion region of n + doped SiC. The scalability of PLD MoS 2 deposition and the electronic transport tunability by implantation doping of SiC represents key steps for industrial development of MoS 2 /SiC devices.

show abstract

Substrate-mediated growth of oriented, vertically aligned MoS2 nanosheets on vicinal and on-axis SiC substrates

Cited by 15 publications

References 39 publications

Improved Ordering of Quasi-Two-Dimensional MoS₂ via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS_2+x

Improved Ordering of Quasi-Two-Dimensional MoS₂ via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS_2+x

2D MoS₂ Heterostructures on Epitaxial and Self‐Standing Graphene for Energy Storage: From Growth Mechanism to Application

Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS₂ on Ion Implantation Doped 4H‐SiC

Contact Info

Product

Resources

About

Substrate-mediated growth of oriented, vertically aligned MoS2 nanosheets on vicinal and on-axis SiC substrates

Cited by 15 publications

References 39 publications

Improved Ordering of Quasi-Two-Dimensional MoS2 via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS2+x

Improved Ordering of Quasi-Two-Dimensional MoS2 via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS2+x

2D MoS2 Heterostructures on Epitaxial and Self‐Standing Graphene for Energy Storage: From Growth Mechanism to Application

Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS2 on Ion Implantation Doped 4H‐SiC

Contact Info

Product

Resources

About

Improved Ordering of Quasi-Two-Dimensional MoS₂ via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS_2+x

Improved Ordering of Quasi-Two-Dimensional MoS₂ via an Amorphous-to-Crystal Transition Initiated from Amorphous Sulfur-Rich MoS_2+x

2D MoS₂ Heterostructures on Epitaxial and Self‐Standing Graphene for Energy Storage: From Growth Mechanism to Application

Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS₂ on Ion Implantation Doped 4H‐SiC