Large‐Area Growth of MoS₂/WS₂ Heterostructures by a Sequential Atomic Layer Deposition and Spin‐Coating Approach

Abstract

research and development in this area has demonstrated a host of different material platforms with unique and precisely tunable properties utilizing various quantum confinement effects. [1][2][3][4] Especially the large surface area of 2D semiconducting materials enables prominent interactions with its environment, resulting in a wide range of possible sensing applications, [5] strong interlayer interactions in van der Waals (vdW) heterostructures, [6] and large exciton binding energies. [7] Transition metal di-chalcogenides (TMDCs) are among the most promising 2D semiconductors, owing to their variable electron energy band gaps [8][9][10] and alignment dependent optoelectronic properties in Moiré heterostructures. [11] TMDC materials also provide an opportunity to form heterostructures with atomically sharp interfaces due to the weak vdW interlayer interactions, making them a perfect platform to investigate interlayer interactions at the atomic scale and to develop lowdimension devices with new functionalities. [12][13][14] Most of the device designs showing unique optoelectronic properties are largely based on layers obtained by mechanical exfoliation, that is, by cleaving from bulk TMDCs crystals, [15][16][17] allowing for an understanding of their fundamental physical properties. However, this approach is not suitable for industrial scale device fabrication. [18] Extensive research efforts are being made on developing and fine tuning bottom-up approaches to grow individual layers of TMDCs single-and few-layer films. In particular, large area (millimeter to centimeter range) growth of TMDC layers has been demonstrated using various types of chemical vapor deposition (CVD), [19][20][21][22] atomic layer deposition (ALD), [23][24][25][26] as well as molecular beam epitaxy, [27][28][29] and solution-based deposition approaches. [22,[30][31][32][33][34][35][36][37] A broad range of physical characteristics have been reported, including film morphology, domain size, and charge mobility. [22,26] For TMDC devices, the controlled growth of vdW heterostructures is a prerequisite, which, however, is challenging due to the weak interaction between the growing layers and, up to now, was only described in a few studies. For example, microscale lateral TMDC heterostructures were obtained by the subsequent growth of two TMDC materials, resulting in dispersed flakes laterally connected in some cases. [38][39][40][41][42][43][44] For Despite the plethora of intriguing phenomena observed in heterostructure stacks of 2D transition metal dichalcogenide (2D-TMDC) flakes, their application in functional devices is still hampered due to the lack of reliable growth methodologies for large-area heterostructures. Here, a scalable process for obtaining as-grown transition metal di-chalcogenide heterostructures by a combination of atomic layer deposition of monolayer MoS 2 and solutionbased processing of ultrathin WS 2 is presented. Spatially uniform optical and electrical characteristics of the individual TMDC layers and heterostructure...

Large area van der Waals MoS2–WS2 heterostructures for visible-light energy conversion

“…61 and in more recent references. 27,[62][63][64][65][66][67][68] We also stress that the absolute photocurrent and photovoltage values which have been measured in our proofof-concept TMD heterojunction are far too low for any realistic electro-optical photoconversion application. This limitation is primarily due to the very high series resistance of the graphene bilayer back contact, in the range of 20 kΩ (more details in ESI † section S4).…”

Heterointerfaces: Unlocking Superior Capacity and Rapid Mass Transfer Dynamics in Energy Storage Electrodes

“…The development of heterogeneous materials synthesis approaches is directed toward more efficient, scalable, and cost-effective methodologies. Techniques such as scalable production of heterostructures on glass fiber fabrics, [87] extrusion-based three-dimensional (3D) printing, [88] high-speed spark plasma sintering, [89] and scalable atomic-layer deposition followed by solution-based synthesis for 2D lateral heterostructures [90] are promising avenues for overcoming these challenges. Enhancing the comprehension of interfacial properties and refining material integration techniques is vital for realizing the full potential of heterogeneous materials.…”

Tip-Enhanced Two-Photon-Excited Fluorescence of Interfacial Charge Transfer Excitons in MoS2/WS2 Heterostructures: Implications for Spectral Measurement of 2D Materials

“…Localized interlayer moiré excitons have been observed in twisted MoS 2 /WS 2 heterostructures and are strongly influenced by the vertical electric field . Numerous preparative techniques, including various chemical vapor deposition (CVD), atomic layer deposition (ALD), and molecular beam epitaxy, are employed for the synthesis of large-scale TMDs and their heterostructures. Plasma, sodium chloride, and WO 3– x /MoO 3– x core–shell nanowire can assist the growth of MoS 2 /WS 2 heterostructures, − and the growth-temperature-mediated CVD method enables the selective syntheses of TMD heterostructures .…”