I want to deposition a dielectric layer on top of the CVD wet transferred graphene. The purpose of the dielectric layer is to uniformly cover the graphene and enable the top-gate modification of graphene. The structure is ITO/dielectric layer/graphene.

So far, I have tried heat-evaporation, E-beam, sputtering of SiO2, and ALD Al2O3. None of them succeed, the top-gate electrodes always short with bottom graphene.

I wonder is there a possible method to achieve this structure?