Time-dependent simulation of particle and displacement currents in THz graphene transistors

Abstract

Although time-independent models provide very useful dynamical information with a reduced computational burden, going beyond the quasi-static approximation provides enriched information when dealing with TeraHertz (THz) frequencies. In this work, the THz noise of dual-gate graphene transistors with DC polarization is analyzed from a careful simulation of the time-dependent particle and displacement currents. From such currents, the power spectral density (PSD) of the total current fluctuations are computed at the source, drain and gate contacts. The role of the lateral dimensions of the transistors, the Klein tunneling and the positive-negative energy injection on the PSD are analyzed carefully. Through the comparison of the PSD with and without Band-to-Band tunneling and graphene injection, it is shown that the unavoidable Klein tunneling and positive-negative energy injection in graphene structures imply an increment of noise without similar increment on the current, degrading the (either low or high frequency) signal-to-noise ratio. Finally, it is shown that the shorter the vertical height (in comparison with the length of the active region in the transport direction), the larger the maximum frequency of the PSD. As a byproduct of this result, an alternative strategy (without length scaling) to optimize the intrinsic cut-off frequency of graphene transistors is envisioned.

arXiv comment22 pages, 9 figures, proceeding of UPoN2015

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Cited by in corpus (4)

• Limitations of the intrinsic cut-off frequency to correctly quantify the speed of nanoscale transistors
• Quantum time-dependent Monte Carlo simulation of electron devices with 2D linear-band materials: a genuine TeraHertz signature for graphene
• Identifying weak values with intrinsic dynamical properties in Modal theories
• Noise and charge discreteness as ultimate limit for the THz operation of ultra-small electronic devices