Hi,
I am trying to fabricate photo-detectors based on 2D black phosphorous material. The Au/Cr contacts are deposited by e-beam on top of BP flakes. I was wondering if anyone could mention the detailed procedure and highlight the common problems that we can encounter during such fabrication of contacts on top of 2D materials.
Thanks for your anticipation.
Hello Mohammed Zia Ullah Khan ,
Generally depositing metals like Cr and Au should be simple. I would imagine that any complications would arise from the fragility of your black phosphorous flakes.
What are the size of your contact pads? What thicknesses are you aiming for. I would suggest a 3-5 nm for the Cr adhesion layer followed by 60 nm or more for the Au contact.
Ensure your sample is clean. Maybe a quick and simple UV-Ozone treatment prior to evaporation would be best.
Make sure the deposition rate is not too fast and monitor the chamber temperature and pressure.
You may also want to consider replacing the Cr adhesion layer to a Ti adhesion layer. The evaporation of Ti also provides a gettering effect, improving the vacuum quality.
You may want to take a look at my answer from the following RG question:
https://www.researchgate.net/post/How_thick_should_Ti_adhesion_layer_be
hi,
Something similar we tried with a 2D material. The 2D sheet was roughly few tens of micrometer long. It was manually deposited through droplet suspension method on a non conducting substrate. It was then coated with thermal PVD process using Al coating. Physical mask was used to create non ohmic region on it. Initial trials gave a non consistent ohmic contact with the 2D material. We empirically found out that it was the thin metallic coat which was not making the ohmic contact with the side walls of the 2D sheet. After increasing the amount of Al coating at the time of thermal PVD process, we were able to get better and consistent ohmic contacts for the same. In your case since already you are using e beam evaporation, my money is on the same problem. Try and increase the amount of deposited metal on to the 2D sheet.
Regards
Amit Morarka Sir, can you provide me reference/pdf of your work that you have done with 2D materials that you have mentioned here? actually i am also facing same problem.
thanks
hi,
Sorry to inform you but that work did not get to see the light of any journal. I would suggest you to get some insights from other published work or go through rigorous trial error method to get the results!!!
Regards
- Badges
- Science topic