TY - JOUR
T1 - Clean Transfer of 2D Transition Metal Dichalcogenides Using Cellulose Acetate for Atomic Resolution Characterizations
AU - Zhang, Tianyi
AU - Fujisawa, Kazunori
AU - Granzier-Nakajima, Tomotaroh
AU - Zhang, Fu
AU - Lin, Zhong
AU - Kahn, Ethan
AU - Perea-López, Néstor
AU - Elías, Ana Laura
AU - Yeh, Yin Ting
AU - Terrones, Mauricio
N1 - Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/8/23
Y1 - 2019/8/23
N2 - Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs) can be easily synthesized on SiO2/Si substrates by chemical vapor deposition (CVD). However, for practical applications, those 2D crystals usually need to be retrieved and placed onto target substrates. Hence, a robust and effective transfer process is required. Currently, the most widely used approach for transferring CVD-grown TMDs involves the spin-coating of a poly(methyl methacrylate) (PMMA) support layer, followed by the wet etching of the SiO2 layer in hot NaOH. This transfer process often causes substantial accumulation of polymer residues as well as severe structural damage of TMDs induced during the etching of substrates at elevated temperatures. In this work, we present an alternative approach for the transfer of CVD-grown TMDs that can address the issues mentioned above. In this process, we replaced PMMA with cellulose acetate (CA) as a support layer and used buffered oxide etch (BOE) as an effective room-temperature etchant for SiO2. The CA-transferred TMDs exhibit well-preserved structural integrity and unaltered optical properties as well as largely improved microscale and nanoscale cleanliness with reduced wrinkles and cracks. Furthermore, we integrated our CA-transfer method with a deterministic positioning system that allowed microprecision transfer of the TMD layers. For example, a WS2-MoS2 vertical heterojunction with an electronically coupled and uniform interface was successfully created. The CA-transfer technique developed in this work represents a cleaner alternative to the PMMA-transfer method, thus permitting atomic resolution characterizations and the implementation of novel applications of CVD-grown TMDs and their heterostructures.
AB - Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs) can be easily synthesized on SiO2/Si substrates by chemical vapor deposition (CVD). However, for practical applications, those 2D crystals usually need to be retrieved and placed onto target substrates. Hence, a robust and effective transfer process is required. Currently, the most widely used approach for transferring CVD-grown TMDs involves the spin-coating of a poly(methyl methacrylate) (PMMA) support layer, followed by the wet etching of the SiO2 layer in hot NaOH. This transfer process often causes substantial accumulation of polymer residues as well as severe structural damage of TMDs induced during the etching of substrates at elevated temperatures. In this work, we present an alternative approach for the transfer of CVD-grown TMDs that can address the issues mentioned above. In this process, we replaced PMMA with cellulose acetate (CA) as a support layer and used buffered oxide etch (BOE) as an effective room-temperature etchant for SiO2. The CA-transferred TMDs exhibit well-preserved structural integrity and unaltered optical properties as well as largely improved microscale and nanoscale cleanliness with reduced wrinkles and cracks. Furthermore, we integrated our CA-transfer method with a deterministic positioning system that allowed microprecision transfer of the TMD layers. For example, a WS2-MoS2 vertical heterojunction with an electronically coupled and uniform interface was successfully created. The CA-transfer technique developed in this work represents a cleaner alternative to the PMMA-transfer method, thus permitting atomic resolution characterizations and the implementation of novel applications of CVD-grown TMDs and their heterostructures.
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U2 - 10.1021/acsanm.9b01257
DO - 10.1021/acsanm.9b01257
M3 - Article
AN - SCOPUS:85072963819
SN - 2574-0970
VL - 2
SP - 5320
EP - 5328
JO - ACS Applied Nano Materials
JF - ACS Applied Nano Materials
IS - 8
ER -