Graphene base heterojunction transistor: An explorative study on device potential, optimization, and base parasitics

Valerio Di Lecce, Roberto Grassi, Antonio Gnudi, Elena Gnani, Susanna Reggiani, Giorgio Baccarani

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The Graphene-Base Heterojunction Transistor (GBHT) is a novel device concept with a high potential for analog high-frequency RF operation, in which the current is due to both thermionic emission and tunneling. In this paper we study through numerical simulations the influence of previously uninvestigated aspects of Si- and Ge-based GBHTs - namely, crystallographic orientation and doping density values - on the device performance; a comparison with an aggressively scaled HBT structure is then reported. The simulations are carried out with an in-house developed code based on a 1-D quantum transport model within the effective mass approximation and the assumptions of ballistic transport with non-parabolic corrections and ideal semiconductor-graphene interface. We show that crystallographic orientation has a negligible effect on the GBHT performance. The doping density values in the GBHT emitter and collector regions can be tailored to maximize the device performance: the Si device shows better overall performance than the Ge one, yielding a peak cut-off frequency fT higher than 4 THz together with an intrinsic voltage gain above 10, or even higher fT at the cost of a lower gain. The Si-based GBHT can potentially outperform the SiGe HBT by a 2.8 higher fT. For a Si-based GBHT with a circular active region of diameter 50-100 nm, a theoretical balanced value for fT and fmax above 2 THz can be achieved, provided the base parasitics are carefully minimized.

Original languageEnglish (US)
Pages (from-to)23-29
Number of pages7
JournalSolid-State Electronics
Volume114
DOIs
StatePublished - Jul 30 2015

Bibliographical note

Funding Information:
This work has been supported by the EU project GRADE 317839.

Publisher Copyright:
© 2015 Elsevier Ltd. All rights reserved.

Keywords

  • Base parasitics
  • Cut-off frequency
  • Graphene
  • Orientation
  • Simulation
  • Transistor

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