Short channel effects in graphene-based field effect transistors targeting radio-frequency applications
Feijoo, Pedro Carlos (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Jiménez Jiménez, David (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Cartoixà Soler, Xavier (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Fecha:	2016
Resumen:	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 twodimensional (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. Wehave 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 máximum 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.
Ayudas:	European Commission 696656 Ministerio de Economía y Competitividad TEC2015-67462-C2-1-R Ministerio de Economía y Competitividad TEC2012-31330 Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-384
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió acceptada per publicar
Materia:	Graphene ; Field effect transistor ; Short channel effects ; Negative differential resistance ; Radio-frequency
Publicado en:	2D materials, Vol. 3, no. 2 (June 2016) , p. 1-13, ISSN 2053-1583

DOI: 10.1088/2053-1583/3/2/025036

Post-print 33 p, 1.1 MB

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