Novel Mixed-Dimensional hBN-Passivated Silicon Nanowire Reconfigurable Field Effect Transistors: Fabrication and Characterization

Sayantan Ghosh; Muhammad Bilal Khan; Phanish Chava; Kenji Watanabe; Takashi Taniguchi; Slawomir Prucnal; René Hübner; Thomas Mikolajick; Artur Erbe; Yordan M Georgiev

doi:10.1021/acsami.3c04808

Novel Mixed-Dimensional hBN-Passivated Silicon Nanowire Reconfigurable Field Effect Transistors: Fabrication and Characterization

ACS Appl Mater Interfaces. 2023 Aug 30;15(34):40709-40718. doi: 10.1021/acsami.3c04808. Epub 2023 Aug 22.

Authors

Sayantan Ghosh^{1

2}, Muhammad Bilal Khan¹, Phanish Chava^{1

2}, Kenji Watanabe³, Takashi Taniguchi³, Slawomir Prucnal¹, René Hübner¹, Thomas Mikolajick^{2

4

5}, Artur Erbe^{1

2

5}, Yordan M Georgiev^{1

6}

Affiliations

¹ Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, Dresden 01328, Germany.
² Technische Universität Dresden, Dresden 01069, Germany.
³ National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁴ Namlab gGmbH, Nöthnitzer Strasse 64, Dresden 01187, Germany.
⁵ Technische Universität Dresden, Center for Advancing Electronics Dresden (CfAED), Dresden 01069, Germany.
⁶ Institute of Electronics at the Bulgarian Academy of Sciences, 72 Tsarigradsko chaussee blvd, Sofia 1784, Bulgaria.

Abstract

This work demonstrates the novel concept of a mixed-dimensional reconfigurable field effect transistor (RFET) by combining a one-dimensional (1D) channel material such as a silicon (Si) nanowire with a two-dimensional (2D) material as a gate dielectric. An RFET is an innovative device that can be dynamically programmed to perform as either an n- or p-FET by applying appropriate gate potentials. In this work, an insulating 2D material, hexagonal boron nitride (hBN), is introduced as a gate dielectric and encapsulation layer around the nanowire in place of a thermally grown or atomic-layer-deposited oxide. hBN flake was mechanically exfoliated and transferred onto a silicon nanowire-based RFET device using the dry viscoelastic stamping transfer technique. The thickness of the hBN flakes was investigated by atomic force microscopy and transmission electron microscopy. The ambipolar transfer characteristics of the Si-hBN RFETs with different gating architectures showed a significant improvement in the device's electrical parameters due to the encapsulation and passivation of the nanowire with the hBN flake. Both n- and p-type characteristics measured through the top gate exhibited a reduction of hysteresis by 10-20 V and an increase in the on-off ratio (I_ON/I_OFF) by 1 order of magnitude (up to 10⁸) compared to the values measured for unpassivated nanowire. Specifically, the hBN encapsulation provided improved electrostatic top gate coupling, which is reflected in the enhanced subthreshold swing values of the devices. For a single nanowire, an improvement up to 0.97 and 0.5 V/dec in the n- and p-conduction, respectively, is observed. Due to their dynamic switching and polarity control, RFETs boast great potential in reducing the device count, lowering power consumption, and playing a crucial role in advanced electronic circuitry. The concept of mixed-dimensional RFET could further strengthen its functionality, opening up new pathways for future electronics.

Keywords: ambipolar; flash lamp annealing; hBN encapsulation; mixed-dimensional reconfigurable FET; nickel silicide; subthreshold swing.