Hello dear researchers, has anyone experience in obtaining the monolayer of material MoTe2 successfully by the mechanical exfoliation method ?? I have tried a lot of times, but the best thinner sample i get still consists of 5 to 7 layers. My goal is to achieve a monolayer sample of MoTe2 (2H phase-Semiconductor phase). If any one has some experience of getting the monolayer of MoTe2. Please share your tricks and experiences. Thanks
Hi Kaleem,
In my experience of exfoliating TMDs, major tips would be:
1. Use actual Scotch tape (not off-brand), or a special blue-colored clean room-grade tape.
2. Fold the two ends of the tape into the sticky side to use as handles. Take a large flake of the bulk crystal of your TMD (2 x 2 mm in area) and place it in the middle of the tape (length = 15 cm, width = 1.5 cm).
3. As you fold the tape over, migrate the original large flake out from the middle parts towards one edge of the tape and then towards the other. The whole tape should be covered in MoTe2 in about 20 folds in this way, with most of it see-through if you look through it under the light. If it's visibly dark/black, you need to keep folding until it's grey/translucent. As you peel the tape apart from itself on every fold make sure you do it gently/slowly.
4. Find a part that is translucent under the light and press it down with your finger on a pre-cleaned (Acetone + IPA + DI water) SiO2 substrate on a glass slide. Rub the tape into the substrate with your fingertip to make sure it sticks (don't use tweezers to press it down).
5. Use a soft rubber object (like a dust blower or similar) and bang on the chip/glass slide lightly for ten minutes. Sounds stupid - I know, but it works.
6. After ten minutes of this, peel off the tape using tweezers from the chip as slow as you can. This is probably the most important step. Try to do it for ten minutes if you can; it is really difficult as the tape will detach anyway, so try not to use force - just hold the tape up and let it slowly come off the chip at a rate decided by the trembling of your hands (yep).
In this way you should be able to get a few large area monolayers of any TMD on SiO2, though the heavier chalcogenides like those containing Te tend to be more resistant to easy peeling.
Good luck!
Hi Kaleem,
In my experience of exfoliating TMDs, major tips would be:
1. Use actual Scotch tape (not off-brand), or a special blue-colored clean room-grade tape.
2. Fold the two ends of the tape into the sticky side to use as handles. Take a large flake of the bulk crystal of your TMD (2 x 2 mm in area) and place it in the middle of the tape (length = 15 cm, width = 1.5 cm).
3. As you fold the tape over, migrate the original large flake out from the middle parts towards one edge of the tape and then towards the other. The whole tape should be covered in MoTe2 in about 20 folds in this way, with most of it see-through if you look through it under the light. If it's visibly dark/black, you need to keep folding until it's grey/translucent. As you peel the tape apart from itself on every fold make sure you do it gently/slowly.
4. Find a part that is translucent under the light and press it down with your finger on a pre-cleaned (Acetone + IPA + DI water) SiO2 substrate on a glass slide. Rub the tape into the substrate with your fingertip to make sure it sticks (don't use tweezers to press it down).
5. Use a soft rubber object (like a dust blower or similar) and bang on the chip/glass slide lightly for ten minutes. Sounds stupid - I know, but it works.
6. After ten minutes of this, peel off the tape using tweezers from the chip as slow as you can. This is probably the most important step. Try to do it for ten minutes if you can; it is really difficult as the tape will detach anyway, so try not to use force - just hold the tape up and let it slowly come off the chip at a rate decided by the trembling of your hands (yep).
In this way you should be able to get a few large area monolayers of any TMD on SiO2, though the heavier chalcogenides like those containing Te tend to be more resistant to easy peeling.
Good luck!
Thank you very much dear @ Jakub Jadwiszczak . I just want to add one comment here that for getting monolayer, you also need to be lucky :).
Thank you very much, dear , Kaleem Ullah .and Jakub Jadwiszczak
I just want to ask you about MoTe2 that you got by mechanical exfoliation method, is it stable or not?
And what is the difference between those obtained by mechanical exfoliation method, and CVD method?
Thank you in advance.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructures
- Thin Films