Insights into Cold Source MOSFETs with Sub-60 mV/decade and Negative Differential Resistance Effect

TL;DR

This paper explores cold metal 2D material-based FETs that achieve sub-60 mV/decade subthreshold swing, negative differential resistance, and high on-state current, offering promising solutions for future sub-5 nm logic devices.

Contribution

It demonstrates the potential of cold metal 2D materials in FETs to simultaneously realize sub-60 mV/dec SS, NDR effect, and high current, advancing beyond prior device capabilities.

Findings

Achieved sub-60 mV/decade SS in cold metal FETs.

Recorded peak current of 4110 A/m in NbS2/MoS2 heterojunction.

Obtained high PVR with TaS2/MoS2 FET at room temperature.

Abstract

To extend the Moores law in the 5 nm node, a large number of two dimensional (2D) materials and devices have been thoroughly researched, among which the cold metals 2H MS2 (M = Nb, Ta) with unique band structures are expected to achieve the sub-60 mV/dec subthreshold swing (SS). The studied cold metal field-effect transistors (CM-FETs) based on the cold metals are capable to fulfill the high-performance (HP) and low-dissipation (LP) goals simultaneously, as required by the International Technology Roadmap for Semiconductors (ITRS). Moreover, gaps of cold metals also enable the CM-FETs to realize negative differential resistance (NDR) effect. Owing to the wide transmission path in the broken gap structure of NbS2/MoS2 heterojunction, the recording 4110 A/m peak current, several orders of magnitude higher than the tunneling current of the Esaki diode, is achieved by NbS2/MoS2 CM-FET. The largest peak-valley ratio (PVR) is obtained by TaS2/MoS2 CM-FET with VGS = -1V at room temperature. Our results claim that the superior on-state current, SS, cut-off frequency and NDR effect can be obtained by CM-FETs simultaneously. The study of CM-FETs provides a practicable solution for state-of-the-art logic device in sub 5 nm node for both more Moore roadmap and more than Moore roadmap applications.