Short channel effects in graphene-based field effect transistors targeting radio-frequency applications

Abstract

Channel length scaling in graphene field effect transistors (GFETs) is key in the pursuit of higher performance in radio frequency electronics for both rigid and flexible substrates. Although two-dimensional (2D) materials provide a superior immunity to Short Channel Effects (SCEs) than bulk materials, they could dominate in scaled GFETs. In this work, we have developed a model that calculates electron and hole transport along the graphene channel in a drift-diffusion basis, while considering the 2D electrostatics. Our model obtains the self-consistent solution of the 2D Poisson's equation coupled to the current continuity equation, the latter embedding an appropriate model for drift velocity saturation. We have studied the role played by the electrostatics and the velocity saturation in GFETs with short channel lengths L. Severe scaling results in a high degradation of GFET output conductance. The extrinsic cutoff frequency follows a 1/L^n scaling trend, where the index n fulfills n < 2. The case n = 2 corresponds to long-channel GFETs with low source/drain series resistance, that is, devices where the channel resistance is controlling the drain current. For high series resistance, n decreases down to n= 1, and it degrades to values of n < 1 because of the SCEs, especially at high drain bias. The model predicts high maximum oscillation frequencies above 1 THz for channel lengths below 100 nm, but, in order to obtain these frequencies, it is very important to minimize the gate series resistance. The model shows very good agreement with experimental current voltage curves obtained from short channel GFETs and also reproduces negative differential resistance, which is due to a reduction of diffusion current.

arXiv comment27-pages manuscript (10 figures) plus 6 pages of supplementary information. European Union Action H2020 (696656) / Department d'Universitats, Recerca i Societat de la Informació of the Generalitat de Catalunya (2014 SGR 384) / Ministerio de Economía y Competitividad of Spain (TEC2012-31330 and TEC2015-67462-C2-1-R) / MINECO FEDER

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Cited by in corpus (14)

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• Radio frequency performance projection and stability trade-off of h-BN encapsulated graphene field-effect transistors
• A small-signal GFET equivalent circuit considering an explicit contribution of contact resistances
• GFET Asymmetric Transfer Response Analysis through Access Region Resistances
• An efficient GFET structure
• Does carrier velocity saturation help to enhance fmax in graphene field-effect transistors?
• Contact resistance extraction of graphene FET technologies based on individual device characterization
• A Scalable Compact Model for the Static Drain Current of Graphene FETs
• Unveiling the impact of the bias-dependent charge neutrality point on graphene-based multi-transistor applications
• Non-quasi-static effects in graphene field-effect transistors under high-frequency operation
• Graphene on Silicon Hybrid Field-Effect Transistors
• Multi-scale analysis of radio-frequency performance of 2D-material based field-effect transistors