Staircase-like transfer characteristics in multilayer MoS2 field-effect transistors

TL;DR

This paper reports staircase-like transfer characteristics in multilayer MoS2 FETs, attributed to thickness variations and charge transfer effects, highlighting the importance of uniform channel thickness for device performance.

Contribution

It uncovers the origin of staircase-like transfer characteristics in multilayer MoS2 FETs, emphasizing the role of channel thickness uniformity and edge effects.

Findings

Staircase-like transfer characteristics observed in multilayer MoS2 FETs.

Thinner terraces at flake edges cause threshold voltage shifts.

Uniformity of channel thickness is crucial for optimal FET performance.

Abstract

Layered semiconductors, such as MoS2, have attracted interest as channel materials for post-silicon and beyond-CMOS electronics. Much attention has been devoted to the monolayer limit, but the monolayer channel is not necessarily advantageous in terms of the performance of field-effect transistors (FETs). Therefore, it is important to investigate the characteristics of FETs that have multilayer channels. Here, we report the staircase-like transfer characteristics of FETs with exfoliated multilayer MoS2 flakes. Atomic force microscope characterizations reveal that the presence of thinner terraces at the edges of the flakes accompanies the staircase-like characteristics. The anomalous staircase-like characteristics are ascribable to a difference in threshold-voltage shift by charge transfer from surface adsorbates between the channel center and the thinner terrace at the edge. This study reveals the importance of the uniformity of channel thickness.