Mobility Degradation and Series Resistance in Graphene Field-Effect Transistors

Abstract

Accurate device models and parameter extraction methods are of utmost importance for characterizing graphene FETs (GFETs) and for predicting their performance in circuit applications. For dc characterization, accurate extraction of mobility and series resistance is of particular concern. In this article, we show how a first-order mobility degradation model can be used to separate information about mobility degradation and series resistance for a set of GFETs of different channel lengths. Data from a large set of top-gated GFETs based on chemical vapor deposited (CVD) graphene was analyzed to validate the proposed model and extraction procedures. For removing any uncertainties caused by the observed device-to-device data variations due to the uneven quality of CVD graphene, the same methods were applied to a set of closely located bottom-gated GFETs found in literature. Those GFETs were designed for transfer length methods and fabricated on exfoliated graphene of homogeneous quality. Similar mobility degradation behavior was observed for both sets of devices with the mobility being reduced to half for a voltage-induced charge carrier density of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> .