PVA was chosen as a buffer layer because it contains both the polar moieties (C–O bonds) capable of bonding to the polar HfO2 and the nonpolar moieties (C–H bonds) to interface with non-polar graphene. Also, a linear PVA chain makes it possible for its C–O bonds to orient towards the HfO2 en masse while its C–H bonds orient towards the graphene. Finally, the oxygen atoms in PVA are able to bond to the Hf atoms at the interface, which, to first order, closely mimics the bonding structure of Hf atoms in the HfO2 bulk.

In each case the mobility of Si-face and C-face graphene increased after incorporating PVA/HfO2 dielectrics. The mobility of Si-face graphene (~90%) increases much more than that of C-face graphene (~20%). The researchers speculate that the mobility improvement arises from the suppression of random potential fluctuations at the HfO2–PVA interface by chemically passivating the Hf centers.

The groups based at Cornell University, The University of Wisconsin-Stevens Point and Hanyang University are working towards implementing high-speed graphene devices on large-scale substrates.

Further information can be found in the journal Nanotechnology.