Junctionless Electric-Double-Layer MoS₂ Field-Effect Transistor with a Sub-5 nm Thick Electrostatically Highly Doped Channel

Abstract

Junctionless transistors are suitable for sub-3 nm applications because of their extremely simple structure and high electrical performance, which compensate for short-channel effects. Two-dimensional semiconductor transition-metal dichalcogenide materials, such as MoS2, may also resolve technical and fundamental issues for Si-based technology. Here, we present the first junctionless electric-double-layer field-effect transistor with an electrostatically highly doped 5 nm thick MoS2 channel. A double-gated MoS2 transistor with an ionic-liquid top gate and a conventional bottom gate demonstrated good transfer characteristics with a 104 on–off current ratio, a 70 mV dec–1 subthreshold swing at a 0 V bottom-gate bias, and drain-current versus top-gate-voltage characteristics were shifted left significantly with increasing bottom-gate bias due to an electrostatically increased overall charge carrier concentration in the MoS2 channel. When a bottom-gate bias of 80 V was applied, a shoulder and two clear peak features were identified in the transconductance and its derivative, respectively; this outcome is typical of Si-based junctionless transistors. Furthermore, the decrease in electron mobility induced by a transverse electric field was reduced with increasing bottom-gate bias. Numerical simulations and analytical models were used to support these findings, which clarify the operation of junctionless MoS2 transistors with an electrostatically highly doped channel.

Negative Differential Interlayer Resistance in WSe2 Multilayers via Conducting Channel Migration with Vertical Double-Side Contacts

“…17,19,32,33 For example, Jeon et al systematically investigated the volume and surface accumulation conduction of silicon junctionless transistors by demonstrating the doping concentration-dependent g m and dg m curves. 32 In addition, Balestra et al demonstrated the separation of surface and volume inversion in double-gate silicon-on-insulator transistors with respect to the top and bottom electrostatic gate potentials. 33 Seo et al examined the presence of top-and bottom-surface channels along the thickness in 2D vdW multilayers upon the observation of two plateaus in their transconductance curves.…”

“…Previous theoretical calculations and experiments have reported that the variation in the shape and amplitude of g m and d g m behaviors are closely linked to the carrier transport mechanisms. ,,, For example, Jeon et al systematically investigated the volume and surface accumulation conduction of silicon junctionless transistors by demonstrating the doping concentration-dependent g m and d g m curves . In addition, Balestra et al demonstrated the separation of surface and volume inversion in double-gate silicon-on-insulator transistors with respect to the top and bottom electrostatic gate potentials .…”

Performance assessment of monolayer Black Phosphorus DG-JLFET

“…and all are greater than the IRDS 2021 requirements for high performance (HP) technologies. It is also noted that for the p-type doping concentrations13 1.66 10  cm -2 ON-state performance is also satisfied for HD application benchmark requirements. Further, the JLFET performance not significantly affected by the variations in ds V in the ranges 0.03 0…”

“…Furthermore, unlike few-layer MoS2, which typically displays n-type behavior, BP can be modulated into both p-type and n-type structures thanks to its rather small band gap. [13]. The phosphorus atoms in BP create a covalent bond with three nearby atoms, however unlike graphene, BP takes the form of a puckered structure with ridges that are not in the plane.…”

Performance assessment of monolayer Black Phosphorus DG-JLFET

“…Furthermore, unlike few-layer MoS2, which typically displays n-type behavior, BP can be modulated into both p-type and n-type structures thanks to its rather small band gap. [13]. The phosphorus atoms in BP create a covalent bond with three nearby atoms, however unlike graphene, BP takes the form of a puckered structure with ridges that are not in the plane.…”