Mobility overestimation in MoS$_2$ transistors due to invasive voltage probes

TL;DR

This paper demonstrates that previously reported high mobilities in rippled MoS$_2$ transistors are likely overestimated due to invasive voltage probes causing measurement artifacts, highlighting the importance of measurement techniques.

Contribution

It reveals that invasive voltage probes can artificially inflate mobility measurements in MoS$_2$ transistors, challenging prior high mobility claims.

Findings

Invasive probes cause positive threshold voltage shifts.

Measurement artifacts lead to overestimated mobility.

Proper measurement techniques are crucial for accurate mobility assessment.

Abstract

Improving carrier mobilities of two-dimensional (2D) semiconductors is highly sought after. Recently, Ng. et al. [1] reported rippled molybdenum disulfide (MoS$_2$) transistors on bulged silicon nitride (SiN$_x$) substrates that exhibit high electron mobilities up to ~900 cm$^2$V$^{-1}$s$^{-1}$. The high mobility values were attributed to the suppression of electron-phonon scattering by the lattice distortion in the rippled MoS$_2$ channel. While the results are compelling, this Matters Arising shows that the mobility values in ref. [1] are likely to be overestimated due to invasive voltage probes in the four-probe measurement setup, which causes a positive threshold voltage shift near the voltage probes and an artificial overestimation of apparent field-effect mobility.