Passivating Graphene and Suppressing Interfacial Phonon Scattering with Mechanically Transferred Large-Area Ga(2)O(3)

[Image: see text] We demonstrate a large-area passivation layer for graphene by mechanical transfer of ultrathin amorphous Ga(2)O(3) synthesized on liquid Ga metal. A comparison of temperature-dependent electrical measurements of millimeter-scale passivated and bare graphene on SiO(2)/Si indicates that the passivated graphene maintains its high field effect mobility desirable for applications. Surprisingly, the temperature-dependent resistivity is reduced in passivated graphene over a range of temperatures below 220 K, due to the interplay of screening of the surface optical phonon modes of the SiO(2) by high-dielectric-constant Ga(2)O(3) and the relatively high characteristic phonon frequencies of Ga(2)O(3). Raman spectroscopy and electrical measurements indicate that Ga(2)O(3) passivation also protects graphene from further processing such as plasma-enhanced atomic layer deposition of Al(2)O(3).