Reconfigurable p-n junction formation and bandgap opening in bilayer graphene using polyethylene oxide and CsClO4 solid polymer electrolyte

An important feature for graphene-based electronics is the ability to create a p-n junction, which is essential for developing low power optoelectronic and novel electronic devices such as Veselago lens and tunneling FETs. Graphene doping is most commonly achieved by using buried, split electrostatic gates
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, applying high local electrical stress,
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and substitutional or chemical doping that creates charge transfer from adsorbents.
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While electrostatic doping using ions is an effective and reconfigurable doping method for 2D materials,
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it has not been previously used to create a p-n junction in graphene. In addition to doping, another major challenge in graphene-based electronics is that channel conduction cannot be switched off by simply changing the gate voltage because of the lack of a bandgap in single-layer graphene. In contrast, a bandgap can be opened in bilayer graphene by breaking the inversion symmetry of the two layers with the help of an applied vertical electric field.
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In this work, we demonstrate a reconfigurable, bilayer graphene p-n junction created by a solid polymer electrolyte without the use of top/back gates. Using the same electrolyte and depositing a top gate, we also open a bandgap in bilayer graphene.