Name: Residue-Free Fabrication of van der Waals Heterostructures of Two-Dimensional Materials (Video) | JoVE Journal
Uploaded: 2025-07-18T15:10:00.000+00:00
Duration: 4 min 57 s
Description: Discover residue-free fabrication of van der Waals heterostructures using two-dimensional materials. This method enables clean assembly of complex multi-layer devices without polymer residues or temperature constraints.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

This research was supported by the National Research Foundation (NRF) of Korea grant funded by the Korea government (the Ministry of Science and ICT) (RS-2022-NR070247 and RS-2023-00218908) and the GIST-MIT Research Collaboration grant funded by the GIST.

The details of the consumables and equipment used in this study are listed in the Table of Materials.
1. Instrumentation for the residue-free fabrication
NOTE: The residue-free fabrication of 2D materials is performed under ambient conditions using a customized dry transfer setup. The setup comprises three main components: a customized optical microscope, an XY-axis sample stage, and an XYZ-axis stamp manipulator (Figure 1A). These components are installed on an anti-vibration table to minimize external disturbance during operation. The setup is manually controlled.
<ol>
	<li>Optical microscope: Equip the customized commercial optical microscope with long working distance objective lenses (5&#215;, 10&#215;, 20&#215;, 50&#215;, and 100&#215;) and a digital camera to achieve appropriate magnification and sufficient processing space. Connect the camera to the computer, confirming compatibility with the data collection software.</li>
	<li>XY-axis sample stage: Assemble two linear translation stages to facilitate precise adjustments of the sample stage in both the X and Y directions. Additionally, install a flat sample holder to properly accommodate the sample above the stage (Figure 1B).</li>
	<li>XYZ-axis stamp manipulator: Assemble three linear translation stages with a right-angle mounting plate to construct an XYZ-axis manipulator with precise adjustments. Then, employ an additional right-angle mounting plate and a magnetic plate to securely fix a stamp with a magnet (Figure 1C). 
	NOTE: The manipulator must be installed close enough to the sample stage to provide adequate access for the stamp. Additionally, the translation stage is capable of moving more than 2 cm in the Z-axis direction.</li>
</ol>
2. Stamp preparation
NOTE: The size of the tape piece used to create the stamps does not significantly affect the process. Additionally, it is recommended to remove the covering film immediately before using the stamp to provide secure adhesion.
<ol>
	<li>Prepare a double-sided tape stamp (pre-exfoliation stamp).
	<ol>
		<li>Cut a piece of double-sided Kapton tape into a 4&#8239;mm &#215; 5&#8239;mm sized rectangular shape (Figure 2A).</li>
		<li>Affix the piece of double-sided tape to the middle edge of a glass slide, and then remove the covering film (Figure 2B).</li>
	</ol>
	</li>
	<li>Prepare a single-sided tape stamp (tape stamp).
	<ol>
		<li>Cut a piece of single-sided tape into a rhombus shape, with each side 5-6&#8239;mm in length (Figure 2C).</li>
		<li>Make it identical to the double-sided tape stamp described in step 2.1.</li>
		<li>Affix the piece of single-sided tape with the adhesive side facing up, ensuring that the narrow vertex extends 1 mm beyond the edge of the glass slide, on the double-sided tape (Figure 2D). 
		NOTE: Since the single-sided tape extends beyond the edge of the glass slide, a tape with high stiffness was selected to minimize bending &#160;while using the stamp.</li>
		<li>Remove the covering film to expose the adhesive surface of the single-sided tape.</li>
	</ol>
	</li>
</ol>
3. Fabrication of residue-free region and single flake
<ol>
	<li>Perform the pre-exfoliation process on a bulk crystal.
	<ol>
		<li>Prepare a piece of bulk crystal using a cotton swab and a razor blade.</li>
		<li>Attach the crystal to the adhesive surface of the pre-exfoliation stamp (Figure 3A). Then, place another pre-exfoliation stamp on top of the crystal to create a sandwich configuration. 
		NOTE: When using pre-exfoliation stamps, it is crucial to ensure that the entire surface of the bulk crystal adheres uniformly to the stamp, which is crucial for obtaining a large and flat surface after the exfoliation process.</li>
		<li>Gently exfoliate and repeat this process 3 to 5 times until a clean and uniform sub-micron-thick crystal is obtained (Figure 3B). 
		NOTE: The number of iterations required in the exfoliation process should be repeated until a sufficiently uniform and thin pre-exfoliated crystal is achieved. This process determines the thickness and quality of the residue-free region that will be obtained subsequently.</li>
	</ol>
	</li>
	<li>Prepare a clean silicon dioxide/silicon (SiO2/Si) substrate. 
	NOTE: To minimize the potential for external residue, the condition of the cleaned substrate was examined using a 100x optical microscope before use. For the visual identification of thin 2D materials, a 300-nm-thick SiO2 is recommended.
	<ol>
		<li>Cut the thermally grown 300-nm-thick SiO2/Si wafer into pieces of 1&#8239;cm &#215; 1 cm using a wafer cutter.</li>
		<li>Immerse the substrates in high-purity electronic-grade acetone and sonicate for 2 min using an ultrasonic cleaner. 
		NOTE: Acetone sonication cleaning is performed inside a fume hood.</li>
		<li>Rinse the substrates with ultrapure deionized water.</li>
		<li>Dry the substrates using a nitrogen blow, followed by placing them on a hot plate set above 100&#8239;&#176;C for at least 5 min to prevent solvent tracing residue.</li>
		<li>Perform oxygen plasma treatment with an oxygen gas flow rate of 100 sccm, a base pressure of 1 &#215; 10-2 Torr, and a power of 100 W. Stabilize the gas flow for 60 s, apply plasma for 10 s, then purge for 20 s and vent for another 20 s.</li>
	</ol>
	</li>
	<li>Acquire the residue-free region (Video 1). 
	NOTE: Video 1 shows the acquisition of a residue-free region from pre-exfoliated h-BN. Figure 2E presents the example image of the instrument to aid in understanding the process. The reason why the tape piece is attached to the middle edge of the glass slide is to minimize interference between the sample stage and the stamp manipulator (distance &#8776; 1 cm).
	<ol>
		<li>Place the pre-exfoliated crystal on the sample stage. 
		NOTE: All samples loaded onto the sample holder are affixed with a double-sided tape.</li>
		<li>Secure the tape stamp with a tilt angle of at least 5&#176; onto the magnetic plate of the stamp manipulator using a magnet. The tilt of the stamp is achieved by using the glass slide stack as support at the rear side of the stamp (Figure 2E). 
		NOTE: This tilt is consistently&#160;used&#160;in all processes involving the tape stamp.</li>
		<li>Align the tape stamp above the pre-exfoliated crystal by adjusting the sample stage.</li>
		<li>Attach the tape stamp to the top surface of the crystal by adjusting the stamp manipulator in the -Z direction (Figure 3C).</li>
		<li>Gently exfoliate the thin residue-free region by adjusting the stamp manipulator in the +Z direction (Figure 3D). 
		NOTE: When exfoliating the residue-free region, simultaneously moving the sample stage in the +X direction results in more stable processing performance by reducing the tension applied to the exfoliating material, which facilitates the attainment of a larger residue-free region. Additionally, only areas not in contact with the tape are considered residue-free regions.</li>
	</ol>
	</li>
	<li>Achieve residue-free single flakes and a residue-free stamp (Video 2 and Video 3). 
	NOTE: Video 2 and Video 3 demonstrate the process of obtaining residue-free single flakes of h-BN and MoS2, respectively.
	<ol>
		<li>Position a cleaned substrate on the sample stage.</li>
		<li>Adhere the residue-free region firmly to the substrate by adjusting the stamp manipulator in the -Z direction (Figure 3E).</li>
		<li>Exfoliate the single flake by adjusting the stamp manipulator in the +Z direction (Figure 3F). 
		NOTE: The flake is exfoliated through vdW interactions with the substrate. Similar to the process of obtaining the residue-free region described in step 3.3.5, it is beneficial to simultaneously move the sample stage in the +X direction to facilitate the delamination of the residue-free flake. A residue-free region can be utilized to obtain single flakes repeatedly. Additionally, the remaining residue-free region serves as the residue-free stamp used for the manipulation of the flakes.</li>
	</ol>
	</li>
</ol>
4. Principles of target flake manipulation: pick-up and release processes
<ol>
	<li>Pick up the target flake using the residue-free stamp.
	<ol>
		<li>Align the residue-free stamp with the target flake by adjusting the stamp manipulator.</li>
		<li>Contact a partial area of the target flake with the residue-free stamp by moving the stamp manipulator in the -Z direction (Figure 4A).</li>
		<li>Lift the target flake with the residue-free stamp by carefully adjusting the stamp in the +Z direction &#160;Figure 4B). 
		NOTE: The vdW adhesion energy between the 2D materials is greater than that between the SiO2 and the 2D materials, enabling the pick-up process.</li>
	</ol>
	</li>
	<li>Release the target flake onto a substrate.
	<ol>
		<li>Place a cleaned substrate on the sample stage.</li>
		<li>Align the picked-up flake to the target position by adjusting the stamp manipulator.</li>
		<li>Firmly contact the entire area of the target flake with the substrate by adjusting the stamp manipulator in the -Z direction (Figure 4C). 
		NOTE: Ensure that sufficient contact is made with the residue-free region of the stamp, while the tape area remains untouched to prevent the formation of unnecessary residue.</li>
		<li>Lay the target flake from the residue-free stamp by adjusting the stamp manipulator in the +X direction &#160;Figure 4D). 
		NOTE: The release process employs movement in the -X direction to apply shear force at the vdW interface between the 2D materials, resulting in superlubricity. Additionally, simultaneously moving the sample stage in the -X direction facilitates a smoother execution of the release process.</li>
	</ol>
	</li>
</ol>
5. Fabrication of residue-free vdW heterostructure assemblies
NOTE: All pick-up and release processes are carried out as described in Section 4 using the MoS2 residue-free stamp. Synthetic MoS2 crystals (flux zone growth) and h-BN crystals (high-pressure anvil cell growth) are used.
<ol>
	<li>Perform step 3 to obtain the required single flakes of MoS2 and h-BN, as well as the residue-free stamp. 
	NOTE: All single flakes are intentionally positioned closely on the substrate for visualization in Video 4.</li>
	<li>Assemble the h-BN/MoS2/h-BN heterostructure through a bottom-up stacking process, referred to as Hetero A (Video 4).
	<ol>
		<li>Pick up the MoS2 flake with the MoS2 residue-free stamp. 
		NOTE: The vdW adhesion energy between 2D materials is greater than that between SiO2 and the 2D materials, allowing for the successful combination of the target flake and residue-free stamp with any pairing of h-BN and MoS2.</li>
		<li>Release it onto the h-BN flake, thus assembling the MoS2/h-BN structure. 
		NOTE: If a portion of the top layer is in contact with the SiO2 substrate during assembly, a more stable release can be achieved. Conversely, if the top layer cannot make contact with the substrate, superlubricity can also occur between the top and bottom layers. In this context, it is essential to minimize the overlapping area between the residue-free stamp and the target flake during the pick-up process to ensure effective release.</li>
		<li>Pick up another h-BN flake and release it on the MoS2/h-BN structure (Figure 5).</li>
	</ol>
	</li>
	<li>Assemble the h-BN/MoS2/h-BN heterostructure through a top-down stacking process, referred to as Hetero B (Video 5).
	<ol>
		<li>Pick up the h-BN flake using the MoS2 residue-free stamp.</li>
		<li>Use the picked-up h-BN flake to cover the MoS2 flake, and then pick up the MoS2 flake with the already picked-up h-BN flake, forming a h-BN/MoS2 structure.</li>
		<li>Release the combined structure onto another h-BN flake (Figure 6). 
		NOTE: To facilitate the subsequent modular stacking process, one layer of the heterostructure was intentionally designed to have a sufficiently large area for the pick-up process.</li>
	</ol>
	</li>
	<li>Assemble Hetero A and Hetero B as a six-layered heterostructure through a modular stacking process (Video 6).
	<ol>
		<li>Pick up the entire Hetero B using the residue-free stamp.</li>
		<li>Release the Hetero B onto the Hetero A. 
		NOTE: Combining two heterostructures leads to disassembly due to contact with each other. Therefore, it is recommended to perform the release process in a single attempt. Additionally, moving the sample stage further in the -X direction enhances the performance of the modular stacking process.</li>
	</ol>
	</li>
</ol>
6. AFM-tip squeezing technique
NOTE: This technique is an optional process designed to enhance assembly and serves as a post-processing method for removing blisters or contamination formed at the heterointerface.
<ol>
	<li>Equip a silicon tip with a high spring constant. 
	NOTE: Non-contact tip is well-suited for the squeezing process.</li>
	<li>Load the sample onto the&#160;AFM stage.</li>
	<li>Set an appropriate applied force at a scan rate of 1 Hz and a Z servo gain of 1. It is recommended to gradually increase the force, beginning with a low value (for instance, between 5 nN and 2000 nN).</li>
	<li>Gradually increase the applied force from 30 nN to 1000 nN during the squeezing process. Adjust the scanning range to cover the entire heterointerface, extending to the edges of each flake, to ensure complete removal of blisters. 
	NOTE: The optimal force for the squeezing process varies depending on the sample thickness and the interface condition.</li>
</ol>

<ol><li>Piacentini, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Stable+Al2O3+encapsulation+of+MoS2-FETs+enabled+by+CVD+grown+h-BN%5BTitle%5D)+AND+%22Adv+Electron+Mater%22%5BJournal%5D)">Stable Al2O3 encapsulation of MoS2-FETs enabled by CVD grown h-BN.</a> Adv Electron Mater. 8 (9), 2200123(2022).</li>
<li>Wu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((scaled+graphene+transistors+on+diamond-like+carbon%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">scaled graphene transistors on diamond-like carbon.</a> Nature. 472 (7341), 74-78 (2011).</li>
<li>Zhang, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Memristors+based+on+two-dimensional+h-BN+materials%3A+synthesis%2C+mechanism%2C+optimization+and+application%5BTitle%5D)+AND+%22NPJ+2D+Mater+Appl%22%5BJournal%5D)">Memristors based on two-dimensional h-BN materials: synthesis, mechanism, optimization and application.</a> NPJ 2D Mater Appl. 8 (1), 81(2024).</li>
<li>Xia, F., Mueller, T., Lin, Y., Valdes-Garcia, A., Avouris, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ultrafast+graphene+photodetector%5BTitle%5D)+AND+%22Nat+Nanotechnol%22%5BJournal%5D)">Ultrafast graphene photodetector.</a> Nat Nanotechnol. 4 (12), 839-843 (2009).</li>
<li>Lopez-Sanchez, O., Lembke, D., Kayci, M., Radenovic, A., Kis, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ultrasensitive+photodetectors+based+on+monolayer+MoS2%5BTitle%5D)+AND+%22Nat+Nanotechnol%22%5BJournal%5D)">Ultrasensitive photodetectors based on monolayer MoS2.</a> Nat Nanotechnol. 8 (7), 497-501 (2013).</li>
<li>Yan, Z., Liu, G., Khan, J. M., Balandin, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Graphene+quilts+for+thermal+management+of+high-power+GaN+transistors%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">Graphene quilts for thermal management of high-power GaN transistors.</a> Nat Commun. 3 (1), 827(2012).</li>
<li>Acerce, M., Voiry, D., Chhowalla, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Metallic+1T+phase+MoS2+nanosheets+as+supercapacitor+electrode+materials%5BTitle%5D)+AND+%22Nat+Nanotechnol%22%5BJournal%5D)">Metallic 1T phase MoS2 nanosheets as supercapacitor electrode materials.</a> Nat Nanotechnol. 10 (4), 313-318 (2015).</li>
<li>He, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fabrication+of+flexible+MoS2+thin-film+transistor+arrays+for+practical+gas-sensing+applications%5BTitle%5D)+AND+%22Small%22%5BJournal%5D)">Fabrication of flexible MoS2 thin-film transistor arrays for practical gas-sensing applications.</a> Small. 8 (19), 2994-2999 (2012).</li>
<li>Geim, A. K., Grigorieva, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Van+der+Waals+heterostructures%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Van der Waals heterostructures.</a> Nature. 499 (7459), 419-425 (2013).</li>
<li>Bellus, M. Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Type-I+van+der+Waals+heterostructure+formed+by+MoS2+and+ReS2+monolayers%5BTitle%5D)+AND+%22Nanoscale+Horiz%22%5BJournal%5D)">Type-I van der Waals heterostructure formed by MoS2 and ReS2 monolayers.</a> Nanoscale Horiz. 2 (1), 31-36 (2017).</li>
<li>Hong, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ultrafast+charge+transfer+in+atomically+thin+MoS2%2FWS2+heterostructures%5BTitle%5D)+AND+%22Nat+Nanotechnol%22%5BJournal%5D)">Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures.</a> Nat Nanotechnol. 9 (9), 682-686 (2014).</li>
<li>Yan, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Esaki+diodes+in+van+der+Waals+heterojunctions+with+broken-gap+energy+band+alignment%5BTitle%5D)+AND+%22Nano+Lett%22%5BJournal%5D)">Esaki diodes in van der Waals heterojunctions with broken-gap energy band alignment.</a> Nano Lett. 15 (9), 5791-5798 (2015).</li>
<li>Withers, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Light-emitting+diodes+by+band-structure+engineering+in+van+der+Waals+heterostructures%5BTitle%5D)+AND+%22Nat+Mater%22%5BJournal%5D)">Light-emitting diodes by band-structure engineering in van der Waals heterostructures.</a> Nat Mater. 14 (3), 301-306 (2015).</li>
<li>Dong, W., Dai, Z., Liu, L., Zhang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Toward+clean+2D+materials+and+devices%3A+Recent+progress+in+transfer+and+cleaning+methods%5BTitle%5D)+AND+%22Adv+Mater%22%5BJournal%5D)">Toward clean 2D materials and devices: Recent progress in transfer and cleaning methods.</a> Adv Mater. 36 (22), 2303014(2024).</li>
<li>Liu, H., Zhao, J., Ly, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clean+transfer+of+two-dimensional+materials%3A+A+comprehensive+review%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Clean transfer of two-dimensional materials: A comprehensive review.</a> ACS Nano. 18 (18), 11573-11597 (2024).</li>
<li>Pettes, M. T., Jo, I., Yao, Z., Shi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Influence+of+polymeric+residue+on+the+thermal+conductivity+of+suspended+bilayer+graphene%5BTitle%5D)+AND+%22Nano+Lett%22%5BJournal%5D)">Influence of polymeric residue on the thermal conductivity of suspended bilayer graphene.</a> Nano Lett. 11 (3), 1195-1200 (2011).</li>
<li>Mondal, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Low+Ohmic+contact+resistance+and+high+on%2Foff+ratio+in+transition+metal+dichalcogenides+field-effect+transistors+via+residue-free+transfer%5BTitle%5D)+AND+%22Nat+Nanotechnol%22%5BJournal%5D)">Low Ohmic contact resistance and high on/off ratio in transition metal dichalcogenides field-effect transistors via residue-free transfer.</a> Nat Nanotechnol. 19 (1), 34-43 (2024).</li>
<li>Wang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((One-dimensional+electrical+contact+to+a+two-dimensional+material%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">One-dimensional electrical contact to a two-dimensional material.</a> Science. 342 (6158), 614-617 (2013).</li>
<li>Wen, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Contamination-free+assembly+of+two-dimensional+van+der+Waals+heterostructures+toward+high-performance+electronics+and+optoelectronics%5BTitle%5D)+AND+%22Appl+Mater+Today%22%5BJournal%5D)">Contamination-free assembly of two-dimensional van der Waals heterostructures toward high-performance electronics and optoelectronics.</a> Appl Mater Today. 43, 102657(2025).</li>
<li>Pizzocchero, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+hot+pick-up+technique+for+batch+assembly+of+van+der+Waals+heterostructures%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">The hot pick-up technique for batch assembly of van der Waals heterostructures.</a> Nat Commun. 7 (1), 11894(2016).</li>
<li>Wang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clean+assembly+of+van+der+Waals+heterostructures+using+silicon+nitride+membranes%5BTitle%5D)+AND+%22Nat+Electron%22%5BJournal%5D)">Clean assembly of van der Waals heterostructures using silicon nitride membranes.</a> Nat Electron. 6 (12), 981-990 (2023).</li>
<li>Lee, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Residue-free+fabrication+of+2D+materials+using+van+der+Waals+interactions%5BTitle%5D)+AND+%22Adv+Mater%22%5BJournal%5D)">Residue-free fabrication of 2D materials using van der Waals interactions.</a> Adv Mater. 37 (21), 2418669(2025).</li>
<li>Lee, G. -H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Flexible+and+transparent+MoS2+field-effect+transistors+on+hexagonal+boron+nitride-graphene+heterostructures%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Flexible and transparent MoS2 field-effect transistors on hexagonal boron nitride-graphene heterostructures.</a> ACS Nano. 7 (9), 7931-7936 (2013).</li>
<li>Lee, G. -H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Highly+stable%2C+dual-gated+MoS2+transistors+encapsulated+by+hexagonal+boron+nitride+with+gate-controllable+contact%2C+resistance%2C+and+threshold+voltage%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Highly stable, dual-gated MoS2 transistors encapsulated by hexagonal boron nitride with gate-controllable contact, resistance, and threshold voltage.</a> ACS Nano. 9 (7), 7019-7026 (2015).</li>
<li>Rokni, H., Lu, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Direct+measurements+of+interfacial+adhesion+in+2D+materials+and+van+der+Waals+heterostructures+in+ambient+air%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">Direct measurements of interfacial adhesion in 2D materials and van der Waals heterostructures in ambient air.</a> Nat Commun. 11 (1), 5607(2020).</li>
<li>Eda, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photoluminescence+from+chemically+exfoliated+MoS2%5BTitle%5D)+AND+%22Nano+Lett%22%5BJournal%5D)">Photoluminescence from chemically exfoliated MoS2.</a> Nano Lett. 11 (12), 5111-5116 (2011).</li>
<li>Ma, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Control+of+hexagonal+boron+nitride+dielectric+thickness+by+single-layer+etching%5BTitle%5D)+AND+%22J+Mater+Chem+C%22%5BJournal%5D)">Control of hexagonal boron nitride dielectric thickness by single-layer etching.</a> J Mater Chem C. 7 (21), 6273-6278 (2019).</li>
<li>Peimyoo, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Laser-writable+high-k+dielectric+for+van+der+Waals+nanoelectronics%5BTitle%5D)+AND+%22Sci+Adv%22%5BJournal%5D)">Laser-writable high-k dielectric for van der Waals nanoelectronics.</a> Sci Adv. 5 (1), eaau0906(2019).</li>
<li>Liang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Impact+of+post-lithography+polymer+residue+on+the+electrical+characteristics+of+MoS2+and+WSe2+field+effect+transistors%5BTitle%5D)+AND+%22Adv+Mater+Interfaces%22%5BJournal%5D)">Impact of post-lithography polymer residue on the electrical characteristics of MoS2 and WSe2 field effect transistors.</a> Adv Mater Interfaces. 6 (3), 1801321(2019).</li>
<li>Xiao, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Atomic-layer+soft+plasma+etching+of+MoS2%5BTitle%5D)+AND+%22Sci+Rep%22%5BJournal%5D)">Atomic-layer soft plasma etching of MoS2.</a> Sci Rep. 6, 19945(2016).</li>
<li>Koperski, M., Vaclavkova, D., Watanabe, K., Taniguchi, T., Novoselov, K. S., Potemski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Midgap+radiative+centers+in+carbon-enriched+hexagonal+boron+nitride%5BTitle%5D)+AND+%22Proc+Natl+Acad+Sci%22%5BJournal%5D)">Midgap radiative centers in carbon-enriched hexagonal boron nitride.</a> Proc Natl Acad Sci. 117 (24), 13214-13219 (2020).</li>
<li>Li, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((From+bulk+to+monolayer+MoS2%3A+Evolution+of+Raman+scattering%5BTitle%5D)+AND+%22Adv+Funct+Mater%22%5BJournal%5D)">From bulk to monolayer MoS2: Evolution of Raman scattering.</a> Adv Funct Mater. 22 (7), 1385-1390 (2012).</li>
<li>Bampoulis, P., Teernstra, V. J., Lohse, D., Zandvliet, H. J. W., Poelsema, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Hydrophobic+Ice+Confined+between+Graphene+and+MoS2%5BTitle%5D)+AND+%22J+Phys+Chem+C%22%5BJournal%5D)">Hydrophobic Ice Confined between Graphene and MoS2.</a> J Phys Chem C. 120 (47), 27079-27084 (2016).</li>
<li>Ghorbanfekr-Kalashami, H., Vasu, K. S., Nair, R. R., Peeters, F. M., Neek-Amal, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dependence+of+the+shape+of+graphene+nanobubbles+on+trapped+substance%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">Dependence of the shape of graphene nanobubbles on trapped substance.</a> Nat Commun. 8 (1), 15844(2017).</li>
<li>Haigh, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cross-sectional+imaging+of+individual+layers+and+buried+interfaces+of+graphene-based+heterostructures+and+superlattices%5BTitle%5D)+AND+%22Nat+Mater%22%5BJournal%5D)">Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices.</a> Nat Mater. 11 (9), 764-767 (2012).</li>
<li>Purdie, D. G., Pugno, N. M., Taniguchi, T., Watanabe, K., Ferrari, A. C., Lombardo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cleaning+interfaces+in+layered+materials+heterostructures%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">Cleaning interfaces in layered materials heterostructures.</a> Nat Commun. 9 (1), 5387(2018).</li>
<li>Rosenberger, M. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Nano-%26%2334%3BSqueegee%26%2334%3B+for+the+creation+of+clean+2D+material+interfaces%5BTitle%5D)+AND+%22ACS+Appl+Mater+Interfaces%22%5BJournal%5D)">Nano-&#34;Squeegee&#34; for the creation of clean 2D material interfaces.</a> ACS Appl Mater Interfaces. 10 (12), 10379-10387 (2018).</li>
<li>Hanbicki, A. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Double+indirect+interlayer+exciton+in+a+MoSe2%2FWSe2+van+der+Waals+heterostructure%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Double indirect interlayer exciton in a MoSe2/WSe2 van der Waals heterostructure.</a> ACS Nano. 12 (5), 4719-4726 (2018).</li>
<li>Liu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Interlayer+friction+and+superlubricity+in+single-crystalline+contact+enabled+by+two-dimensional+flake-wrapped+atomic+force+microscope+tips%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Interlayer friction and superlubricity in single-crystalline contact enabled by two-dimensional flake-wrapped atomic force microscope tips.</a> ACS Nano. 12 (8), 7638-7646 (2018).</li>
<li>Li, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Superlubricity+between+MoS2+monolayers%5BTitle%5D)+AND+%22Adv+Mater%22%5BJournal%5D)">Superlubricity between MoS2 monolayers.</a> Adv Mater. 29 (27), 1701474(2017).</li>
<li>Tian, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Tribo-Induced+interfacial+material+transfer+of+an+atomic+force+microscopy+probe+assisting+superlubricity+in+a+WS2%2Fgraphene+heterojunction%5BTitle%5D)+AND+%22ACS+Appl+Mater+Interfaces%22%5BJournal%5D)">Tribo-Induced interfacial material transfer of an atomic force microscopy probe assisting superlubricity in a WS2/graphene heterojunction.</a> ACS Appl Mater Interfaces. 12 (3), 4031-4040 (2020).</li>
<li>Liang, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((First-principles+study+of+superlubricity+of+two-dimensional+graphene%2FWS2+heterostructures%5BTitle%5D)+AND+%22Tribol+Lett%22%5BJournal%5D)">First-principles study of superlubricity of two-dimensional graphene/WS2 heterostructures.</a> Tribol Lett. 73 (1), 1-9 (2025).</li>
<li>Li, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Superlubricity+of+molybdenum+disulfide+film%5BTitle%5D)+AND+%22Surf+Sci+Technol%22%5BJournal%5D)">Superlubricity of molybdenum disulfide film.</a> Surf Sci Technol. 1 (1), 27(2023).</li>
</ol>

The authors have nothing to disclose.

Leveraging vdW interactions and controlling the direction of applied forces at the vdW interface enables the assembly of structures ranging from residue-free single flakes to heterostructures. In contrast to other approaches, this method eliminates the need for complex infrastructure, stringent fabrication processes, and experimental variables such as exposure to polymers, solvents, or temperature variations23,24. Beyond the fabrication of residue-free single fla...

The rapid development of two-dimensional (2D) materials has significantly transformed numerous research fields, creating unprecedented opportunities for advanced devices. The remarkable properties of these materials, including exceptional electrical conductivity, mechanical strength, and thermal stability, render them ideal candidates for applications in electronic and optoelectronic devices, thermal management solutions, energy storage systems, and sensors1,2,3,4,5,6,7,8. Additionally, the ability to construct van der Waals (vdW) heterostructures enhances their functionality, allowing for precise engineering of band structures and interlayer interactions9,10,11,12,13. This capability can lead to new or improved material properties tailored to specific applications.
However, the handling and manipulation of 2D materials pose considerable challenges, particularly in preserving their exceptional quality during processing. Residue contamination from conventional fabrication techniques can significantly undermine the integrity of the materials, adversely affecting their performance and reliability in devices14,15. The use of polymers in the fabrication of 2D materials often leaves unwanted residues16,17. To address this issue, several researchers have explored advanced fabrication techniques and clean transfer processes to enhance the production of high-purity 2D materials. Wang et al. introduced an innovative assembly technique that leverages vdW adhesion to achieve clean interfaces in graphene/boron nitride heterostructures18. Building on this concept, Wen et al. recently employed a vdW-assisted dry-transfer technique using h-BN as an intermediate layer, which allowed the clean detachment of single flakes by laterally peeling off the vdW layer19. In a notable prior technique, Pizzocchero et al. developed the &#34;hot pick-up&#34; technique for batch assembly of heterostructures, demonstrating rapid and high-yield production of blister-free interfaces by stacking at elevated temperatures20. Additionally, Wang et al. proposed a polymer-free approach using flexible silicon nitride membranes, which allows for clean assembly under ultra-high vacuum and high temperatures21. While previous studies have developed excellent methods, the ability to obtain residue-free single flakes and implement an easy processing method remains essential. Therefore, developing effective methods for residue-free processing is crucial for maximizing the potential of 2D materials in practical applications.
In the previous work by Lee et al., a novel fabrication method was developed that leverages the inherent vdW interactions between 2D materials to obtain single flakes and assemble heterostructures without using polymer support layers22. Comprehensive characterization, including atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and electrical measurements, confirmed the residue-free nature of both the transferred flakes and the resulting heterostructures. Building upon this residue-free transfer platform, the current work provides a detailed and protocol-oriented guide that covers the entire process from experimental setup to the expanded assembly technique of complex heterostructures. Specifically, the setup of a dry transfer system, strategies for stamp preparation, and optimized procedures for obtaining clean and thin flakes of h-BN and MoS2 are detailed. These materials are extensively used due to their strong vdW adhesion and advantageous electronic properties13,23,24,25. Additionally, systematic techniques for sequential pick-up and residue-free release are described, along with various heterostructure assembly techniques such as top-down, bottom-up, and modular stacking processes.
The article is organized as follows: step 1 and step 2 detail the design of the dry transfer system and the fabrication of two types of stamps, which include a pre-exfoliation stamp and a tape stamp. Step 3 outlines the process for producing residue-free flakes using these stamps. Step 4 and step 5 describe the procedures for vertical stacking via residue-free stamp, enabling the construction of complex heterostructures. Finally, step 6 presents an AFM-tip squeezing technique to selectively remove interfacial blisters, thereby enhancing interfacial quality after assembly. Overall, these protocols aim to provide a versatile and reproducible methodology for fabricating clean and high-quality 2D heterostructures.

<table><tbody><tr><td>Atomic force microscope</td><td>Park Systems</td><td>XE-100</td><td></td></tr><tr><td>Confocal Raman microscope</td><td>Horiba</td><td>LabRAM HR Evolution</td><td></td></tr><tr><td>Contact mode AFM tip&amp;nbsp;</td><td>Nanosensors</td><td>PPP-CONTSCR</td><td>For contact mode measurement, Spring constant: 0.2 N/m&amp;nbsp;</td></tr><tr><td>Digital camera</td><td>SONY</td><td>E3ISPM06300KPB</td><td></td></tr><tr><td>Double-sided Kapton tape</td><td>Daehyun ST</td><td>ST-930H</td><td>For attaching the single-sided tape to the glass slide</td></tr><tr><td>h-BN crystal</td><td>2D Semiconductors</td><td>BLK-hBN</td><td>High pressure anvil cell growth</td></tr><tr><td>MoS&lt;sub&gt;2&lt;/sub&gt; crystal</td><td>2D Semiconductors</td><td>BLK-MoS2-SYN</td><td>Synthetic Crystal, flux zone growth</td></tr><tr><td>Non-contact mode AFM tip&amp;nbsp;</td><td>Nanosensors</td><td>PPP-NCHR</td><td>For nano squeezing, High spring constant: 42 N/m</td></tr><tr><td>Optical microscope</td><td>OLYMPUS</td><td>BX51</td><td></td></tr><tr><td>Plasma system&amp;nbsp;</td><td>Femto Science</td><td>CUTE-1MP/R</td><td>For oxygen plasma treatment</td></tr><tr><td>Single-sided tape</td><td>Nitto Denko</td><td>Revalpha RA-98LS(N)</td><td>High stiffness tape</td></tr><tr><td>Ultrasonic cleaner</td><td>Branson</td><td>5510E-DTH</td><td></td></tr></tbody></table>

residue-free fabrication of van der waals heterostructures of two-dimensional materials

Residue-Free Fabrication of van der Waals Heterostructures of Two-Dimensional Materials

In this work, a unique methodology is presented that utilizes van der Waals (vdW) interactions to fabricate residue-free single flakes of two-dimensional (2D) materials, which are subsequently assembled into intricate heterostructures. The approach focuses on ensuring that the flakes are free from any residue that could affect their properties and performance. Evidence from atomic force microscopy and Raman spectroscopy confirms that the transferred hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2) flakes exhibit excellent flatness and strain-free characteristics, which are crucial for various applications in electronics and optoelectronics. Furthermore, the pick-up and release processes of a target flake are demonstrated using a residue-free stamp, controlled by the type of applied force at the interface, whether normal or shear. By carefully directing the movement of the residue-free stamp, successful assembly of h-BN/MoS2/h-BN heterostructures is achieved through both bottom-up and top-down stacking processes. Moreover, pre-assembled heterostructures were modularly stacked to create a more complex heterostructure, showcasing the versatility of the proposed methodology. This work not only enables to achieve residue-free single flakes of 2D materials, but also paves the way for improved fabrication techniques in vdW heterostructures.

The protocol described herein fabricates residue-free single flakes and complex heterostructure assemblies by utilizing exclusively vdW interactions. In the previous study, comprehensive characterizations of the surface morphology, chemical composition, and electrical properties of residue-free MoS2 flakes were conducted22. As shown in Figure 7, HR-TEM was employed to examine the surface structure at the atomic level. The HR...

This study presents a residue-free fabrication methodology for producing single flakes of two-dimensional materials and assembling them into complex heterostructures using only van der Waals interactions. The technique eliminates the need for external substances and specific experimental conditions, enabling complex heterostructure assemblies through bottom-up, top-down, and modular stacking processes.

In this work, a unique methodology is presented that utilizes van der Waals (vdW) interactions to fabricate residue-free single flakes of two-dimensional ...

residue-free-fabrication-van-der-waals-heterostructures-two

Research

JoVE Journal

Engineering

We report a protocol for combining the atomic metrology of the Scanning Tunneling Microscope for surface patterning with selective Atomic Layer Deposition and Reactive Ion Etching. Using a robust process involving numerous atmospheric exposures and transport, 3D nanostructures with atomic metrology are fabricated.

Atomically Traceable Nanostructure Fabrication

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Through the sulfurization of pre-deposited transition metals, large-area and vertical 2D crystal hetero-structures can be fabricated. The film transferring and device fabrication procedures are also demonstrated in this report.

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

A protocol is presented demonstrating a two-step fabrication technique to grow large-sized single-layer rectangular shaped SnSe flakes on low-cost SiO2/Si dielectrics wafers in an atmospheric pressure quartz tube furnace system.

Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

In this paper, we present a protocol to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica.

A Fabrication and Measurement Method for a Flexible Ferroelectric Element Based on Van Der Waals Heteroepitaxy

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Attainment of high-quality Schottky contacts is imperative for achieving efficient gate modulation in heterostructure field effect transistors (HFETs). We present the fabrication methodology and characteristics of Schottky diodes on Zn-polar BeMgZnO/ZnO heterostructures with high-density two dimensional electron gas (2DEG), grown by plasma-assisted molecular beam epitaxy on GaN templates.

Fabrication of Schottky Diodes on Zn-polar BeMgZnO/ZnO Heterostructure Grown by Plasma-assisted Molecular Beam Epitaxy

In this work we describe a technique that is used to create new crystals (van der Waals heterostructures) by stacking ultrathin layered 2D materials with precise control over position and relative orientation.

Fabricating van der Waals Heterostructures with Precise Rotational Alignment

Calculations performed by the Vienna Ab initio Simulation Package can be used to identify the intrinsic electronic properties of nanoscale materials and predict the potential water-splitting photocatalysts.

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

This article presents an optimized, experience-informed protocol for fabricating high-quality graphene-based moiré superlattice devices with precise twist angles, utilizing a modified dry transfer technique based on a highly tunable, custom-built transfer setup.

Optimized Fabrication Procedure for High-Quality Graphene-based Moir&#233; Superlattice Devices

Discover residue-free fabrication of van der Waals heterostructures using two-dimensional materials. This method enables clean assembly of complex multi-layer devices without polymer residues or temperature constraints.

Residue-Free Fabrication of van der Waals Heterostructures of Two-Dimensional Materials

Explore More Videos