Abstract
This work develops the first frequency-dependent small-signal model for graphene electrolyte-gated field-effect transistors (EGFETs). Graphene EGFETs are microfabricated to measure intrinsic voltage gain, frequency response, and to develop a frequency-dependent small-signal model. The transfer function of the graphene EGFET small-signal model is found to contain a unique pole due to a resistive element, which stems from electrolyte gating. Intrinsic voltage gain, cutoff frequency, and transition frequency for the microfabricated graphene EGFETs are approximately 3.1 V/V, 1.9 kHz, and 6.9 kHz, respectively. This work marks a critical step in the development of high-speed chemical and biological sensors using graphene EGFETs.
Highlights
Graphene consists of an atomically thin layer of sp2 -bonded carbon atom arranged in a hexagonal lattice [1,2,3,4]
This ultra-high gate capacitance, which is in the order of μF/cm2, provides graphene electrolyte-gated field-effect transistors (EGFETs) with excellent transconductance performance [17,18]. It raises the concern of impaired frequency response due to high parasitic gate-source and gate-drain capacitances. This is especially concerning in the case of graphene EGFETs because transconductance performance is greatly enhanced by recessing device passivation such that portions of the source and drain contacts are exposed [19]
To the extent of our knowledge, this work develops the first small-signal frequency-dependent model for graphene electrolyte-gated field-effect transistors (EGFETs). This was accomplished by model for graphene electrolyte-gated field-effect transistors (EGFETs)
Summary
Graphene consists of an atomically thin layer of sp2 -bonded carbon atom arranged in a hexagonal lattice [1,2,3,4]. Because graphene exhibits excellent chemical stability and does not form a native oxide like its silicon metal-oxide-semiconductor field-effect transistor (Si-MOSFET) counterparts, graphene electrolyte-gated field-effect transistors (EGFETs) can take full advantage of the ultrahigh gate capacitance resulting from the electric double layer phenomenon [15]. Excellent chemical stability enables a direct interface with many chemical and biological environments [11,13,14,16] This ultra-high gate capacitance, which is in the order of μF/cm , provides graphene EGFETs with excellent transconductance performance [17,18]. It raises the concern of impaired frequency response due to high parasitic gate-source and gate-drain capacitances. This is especially concerning in the case of graphene EGFETs because transconductance performance is greatly enhanced by recessing device passivation such that portions of the source and drain contacts are exposed [19]
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