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

This work demonstratesthe novel concept of a mixed-dimensionalreconfigurable 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 devicethat can be dynamically programmed to perform as either an n- or p-FETby applying appropriate gate potentials. In this work, an insulating2D material, hexagonal boron nitride (hBN), is introduced as a gatedielectric and encapsulation layer around the nanowire in place ofa thermally grown or atomic-layer-deposited oxide. hBN flake was mechanicallyexfoliated and transferred onto a silicon nanowire-based RFET deviceusing the dry viscoelastic stamping transfer technique. The thicknessof the hBN flakes was investigated by atomic force microscopy andtransmission electron microscopy. The ambipolar transfer characteristicsof the Si-hBN RFETs with different gating architectures showed a significantimprovement in the device's electrical parameters due to theencapsulation and passivation of the nanowire with the hBN flake.Both n- and p-type characteristics measured through the top gate exhibiteda reduction of hysteresis by 10-20 V and an increase in theon-off ratio (I (ON)/I (OFF)) by 1 order of magnitude (up to 10(8)) comparedto the values measured for unpassivated nanowire. Specifically, thehBN encapsulation provided improved electrostatic top gate coupling,which is reflected in the enhanced subthreshold swing values of thedevices. For a single nanowire, an improvement up to 0.97 and 0.5V/dec in the n- and p-conduction, respectively, is observed. Due totheir dynamic switching and polarity control, RFETs boast great potentialin reducing the device count, lowering power consumption, and playinga crucial role in advanced electronic circuitry. The concept of mixed-dimensionalRFET could further strengthen its functionality, opening up new pathwaysfor future electronics.

Automated summary

This work introduces the concept of a mixed-dimensional reconfigurable field effect transistor (RFET) by combining a one-dimensional silicon nanowire with a two-dimensional hexagonal boron nitride (hBN) gate dielectric. The hBN encapsulation improves the device's electrical parameters, reducing hysteresis and increasing the on-off ratio. RFETs have great potential in reducing device count and power consumption, and the concept of mixed-dimensional RFET could further enhance their functionality.