Gate-assisted programmable functionalization of epitaxial graphene devices

Since the discovery of graphene, control of its carrier density via doping or functionalization has been a crucial need. However, precise control of the carrier density for epitaxial graphene on SiC remains a challenge. Multiple cycles of doping and characterization are often required before achieving a desired carrier density [1-4]. In this work, we demonstrate a new approach to precisely program the doping level in top-gated epitaxial graphene devices that are exposed to nitric acid vapor before the gate deposition. With the help of an applied gate, the modification of carrier concentration introduced by the nitric acid can be greatly controlled while the corresponding carrier density at zero gate voltage can be reversibly tuned by more than 4×10¹³/cm² across the Dirac point. We note that such manipulation occurs only above a threshold temperature ~230 K. This enables tuning of the Dirac point to the desired gate voltage value. After tuning, one can freeze the doping in the devices by cooling down the sample below 200 K.



1. Y. Yang et al., Small 11, 90 (2015)

2. H. He et al., Nat Commun 9, 3956 (2018)

3. Y. Zhou et al., Nanoscale 9, 8657 (2017)

4. S. Mhatre et al., Phys Rev B 105, 205423 (2022)