Space charge induced electrostatic doping of two-dimensional materials: Graphene as a case study

We introduce a technique that we call Space Charge Doping for electrostatic doping of 2D materials. This technique exploits the presence of mobile ionic species in glass to induce a charge imbalance at the glass-material interface. Ionic mobility in glass is species dependent and also dependent on the temperature and the applied electric field. Mobility of positive sodium ions is increased by heating and an applied electric field causes ion drift. The polarity of the electric field results in accumulation or depletion of sodium ions at the glass surface inducing, respectively, electron or hole doping in the material placed on the surface, in this case graphene. Extremely high doping levels are reached (⁠$>1014 cm−2$⁠) without compromising graphene quality and with reversibility, bipolarity, and stability in time.