Reduced 1/f noise in high-mobility BN-graphene-BN heterostructure transistors

Raman spectroscopy was used to determine the number of atomic planes in the exfoliated graphene samples and verify the quality of the selected flakes. The optical microscopy images of the exfoliated BN and graphene flakes, and the resulting heterostructure are shown in Figure 2 (b-c). The current-voltage (I-V) characteristics of a representative BN-graphene-BN HFET are shown in Figure 3 (a). Both the effective and field-effect mobility extractions gave consistent results and the room-temperature (RT) mobility was determined to be ~30,000 cm²/Vs at 7·10¹¹ cm^-2. The normalized 1/f noise spectral density of the graphene encapsulated device is presented in Figure 3 (b). We found that the channel-area normalized noise spectral density in BN-graphene-BN HFET is factor of ×5 - ×10 smaller than that in typical reference graphene FETs without channel encapsulation. The observed strong noise reduction can be related to screening of the traps in SiO₂ by the BN barrier. Other possible physical mechanisms and prospects of further noise suppression will be discussed at the presentation.