Analysis of the frequency dependent gate capacitance in CNTFETs

A time-dependent effective-mass SchrodingerPoisson solver is used to study the frequency dependence of the gate capacitance of a short Schottky-barrier carbon nanotube field-effect transistor (CNTFET). A delayed (re)charging of the channel causes a (non-quasi-static) drop of the gate capacitance for higher frequencies on a characteristic scale, which can be related to the escape time of the carriers. The impact of Schottky-barriers on the escape time is discussed both analytically and by means of transient simulations. A comparison with experimental data reveals an interesting qualitative similarity.

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