Formation of p-n junction in polymer electrolyte-top gated bilayer graphene transistor

TL;DR

This paper demonstrates the formation of p-n junctions in bilayer graphene transistors using a polymer electrolyte top gate, achieving high gate capacitance and tunable carrier injection, with implications for advanced graphene-based electronic devices.

Contribution

It introduces a novel method of creating p-n junctions in bilayer graphene via electrolyte gating, with detailed analysis of energy gap opening and device behavior.

Findings

High gate capacitance of 1.5 μF/cm^2 achieved

Simultaneous p and n type carrier injection demonstrated

Energy gap between valence and conduction bands estimated

Abstract

We show simultaneous p and n type carrier injection in bilayer graphene channel by varying the longitudinal bias across the channel and the top gate voltage. The top gate is applied electrochemically using solid polymer electrolyte and the gate capacitance is measured to be 1.5 $\mu F/cm^2$, a value about 125 times higher than the conventional SiO$_2$ back gate capacitance. Unlike the single layer graphene, the drain-source current does not saturate on varying the drain-source bias voltage. The energy gap opened between the valence and conduction bands using top and back gate geometry is estimated.