Self-aligned graphene field-effect transistors with polyethyleneimine   doped source/drain access regions
  We report a method of fabricating self-aligned, top-gated graphene field-effect transistors (GFETs) employing polyethyleneimine spin-on-doped source/drain access regions, resulting in a 2X reduction of access resistance and a 2.5X improvement in device electrical characteristics, over undoped devices. The GFETs on Si/SiO$_2$ substrates have high carrier mobilities of up to 6,300 cm$^2$/Vs. Self-aligned spin-on-doping is applicable to GFETs on arbitrary substrates, as demonstrated by a 3X enhancement in performance for GFETs on insulating quartz substrates, which are better suited for radio frequency applications. 
Hema C. P. Movva, Michael E. Ram\'on, Chris M. Corbet, Sushant Sonde,   Sk. Fahad Chowdhury, Gary Carpenter, Emanuel Tutuc, ...
cond-mat.mes-hall cond-mat.mtrl-sci