How can I passivate the graphene surface？So the graphene device can preserve relatively high mobility and no characteristic degradation for a long time in ambient environment！
While you answer this question，please please give the detailed reference！Thank you very much！
How about depositing a metal layer to act as a passivation layer and removing it before your test? Devices should be protected by N2. Good luck to you.
Thank you, Mr Feng,
Actually,the device I want to fabricate has some parts deposited by metal as electrodes. So using metal layer to passivate the graphene is impossible.
Graphene is in essence a surface, this means it is extreme sensitive to dopants, such as the gas moleculars from adsorption. The characteristic can degrade after some time in the ambient environment. Usually the device is tested in vaccum.
My qusetion is whether there are some ways to passivate the graphene surface, So I can fabricate and test the device in ambient environment. If not, I have to encapsulate the device in vaccum.This can cause some difficulties in the MEMS process！
Best regrads
Had you ever try to deposit SiO2 by CVD on top of graphene (if your boss permit you to load chip with metal into PECVD)? Sputtered AlN may also help but maybe it will induce some damage to graphene since sputtering has high energy. Or you can try ALD Al2O3.
I don't how you fabricated you GFET, but it was difficult to get high performance with photolithography since it was difficult to remove PR thoroughly.
There is no need to give a cap to the device. That is too complex.
Thank you very much,Feng,
Can you give some detailed reference about the method you metioned?
We just want to fabricate a sensor, not GFET. But the structure is some kind like the GFET. I do afraid that depositon of oxides, such as Al2O3,SiO2 may introduce some charge impurities, which can increase carrier scattering and decrease the mobility.And we want uniformal graphene, damages may increase the resistivity heavily. That would grately harm the performance of the device. So AIN is impossible.
Recently I read this paper.[utilization of a buffered dielectric to achieve hig field-effect carrier mobility in graphene transistors, nano letter,Vol 9 No 12,4474]. In this paper, the author said they used combination of high-k Al2O3 and low-k ploymer buffer layer to ahcieve high carrier mobility. I want to know whether this method is commonly used. And what is the best way.
BRs.
It is essential to passivate graphene in any kind of graphene-based application. The common method is to deposit a dielectric layer on graphene. For this method you can get some information from top gate GFET fabrication.
You can consult papers in RF-GFET field that published by IBM. They study different dielectric stack(Polymer/dielectric layer & evaporation aluminum/dielectric layer). I think this will help you in your experiment.
BTW: "Graphene Technology with Inverted-T Gate and RF Passives on 200 mm Platform" published by IBM in 2011IEDM mentioned graphene passivation something like you noted earlier.
I hope my this paper will help you: http://pubs.rsc.org/en/content/articlelanding/2015/nr/c4nr07457b
The corresponding news: http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/graphene-devices-stand-the-test-of-time
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