Toward Phonon-Limited Transport in Two-Dimensional Electronics by Oxygen-Free Fabrication

TL;DR

This paper presents an oxygen-free fabrication method that significantly improves the electrical mobility of 2D MoS2 transistors, approaching theoretical limits and highlighting the importance of avoiding oxygen exposure during device manufacturing.

Contribution

The study introduces an oxygen-free process that enhances 2D transistor performance, achieving record mobilities and providing critical insights into oxygen's impact on device stability.

Findings

Record mobilities of 91 and 132 cm2V-1s-1 for mono- and bi-layer MoS2.

Oxygen-free fabrication improves device figures of merit by over tenfold.

Ambient oxygen exposure irreversibly degrades 2D material performance.

Abstract

Future electronics require aggressive scaling of channel material thickness while maintaining device performance. Two-dimensional (2D) semiconductors are promising candidates, but despite over two decades of research, experimental performance still lags theoretical expectations. Here, we develop an oxygen-free approach to push the electrical transport of 2D field-effect transistors toward the theoretical phonon-limited intrinsic mobility. We achieve record carrier mobilities of 91 (132) cm2V-1s-1 for mono- (bi-) layer MoS2 transistors on SiO2 substrate. Statistics from over 60 devices confirm that oxygen-free fabrication enhances key figures of merit by more than an order of magnitude. While previous studies suggest that 2D transition metal dichalcogenides such as MoS2 and WS2 are stable in air, we show that short-term ambient exposure can degrade their device performance through irreversible oxygen chemisorption. This study emphasizes the criticality of avoiding oxygen exposure, offering guidance for device manufacturing for fundamental research and practical applications of 2D materials.