Page 58 - 2021電物系刊

B. MoS2 Transfer

1. Wet Transfer
In the conventional method, a polymer layer (e.g. PMMA) is first attached on
the MoS2/substrate sample. This is a simple, fast, and capable of realizing large-
area two-dimensional material transfer method. ( According to Figure 2.) First, we
cut the substrate into appropriate size, and then spin-coated PMMA on the TMD
surface as a support layer. Then it is exfoliated off in an aqueous solution and
attached to the target substrate( SiO2/ Si).

(1) Cutting the MoS2/sapphire into appropriate size, generally speaking, we will cut
into 1 cm*1 cm.
(2) First, prepare the top-flake exfoliation substrate by spin-coating a PMMA layer.
After the surface is soft baked for 2 minutes, the PMMA on the edge is removed
with a knife.
(3) The PMMA/MoS2/sapphire is dip-floated in 20% NH4OH(aq). The PMMA/MoS2 is
detached and allowed to float in NH4OH(aq) at 80 °C, and the sapphire is sunk.
(4) Use the sapphire to pick up the film into DI water, and then use the target
substrate to pick up the sample and place it on the heater for 5 minutes to
remove moisture.
(5) The PMMA/MoS2/substrate is dip-floated in Acetone for 2 hours to remove
PMMA.
(6) Use Acetone and IPA( Isopropyl alcohol) to remove organic residues in surface.

Figure 2.

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