Roberto Grassi, Tony Low, Antonio Gnudi, Giorgio Baccarani
In this work, we identify a physical mechanism for the phenomenon of negative output differential resistance (NDR) in short-channel graphene FETs (GFETs) through non-equilibrium Green's function (NEGF) simulations. This NDR phenomenon is due to a transport mode bottleneck effect induced by the source and drain contacts, which we further elucidate using a simpler semianalytical ballistic model that captures the essential physics. This NDR effect is found to occur only when the gate biasing produces an n-p-n or p-n-p polarity configuration along the channel, for both positive and negative drain-source voltage sweep. In addition, we also explore the impact on the NDR effect of contact-induced energy broadening in the source and drain regions and a finite contact resistance.
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http://arxiv.org/abs/1208.2156
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