Fe-assisted epitaxial growth of 4-inch single-crystal transition-metal dichalcogenides on c-plane sapphire without miscut angle

TL;DR

This paper presents a novel epitaxial method to grow 4-inch single-crystal Fe-doped transition-metal dichalcogenides on sapphire without miscut, achieving high mobility and device performance for 2D semiconductors.

Contribution

The authors develop an innovative epitaxial strategy enabling wafer-scale growth of single-crystal TMDCs on industry-compatible sapphire without miscut, combining synthesis and doping.

Findings

Achieved 4-inch single-crystal Fe-doped TMDC monolayers on sapphire.

Demonstrated ultrahigh electron mobility (~86 cm2 V-1 s-1).

Obtained high on/off current ratio (~10^8).

Abstract

Epitaxial growth and controllable doping of wafer-scale single-crystal transition-metal dichalcogenides (TMDCs) are two central tasks for extending Moore's law beyond silicon. However, despite considerable efforts, addressing such crucial issues simultaneously under two-dimensional (2D) confinement is yet to be realized. Here we design an ingenious epitaxial strategy to synthesize record-breaking 4-inch single-crystal Fe-doped TMDCs monolayers on industry-compatible c-plane sapphire without miscut angle. In-depth characterizations and theoretical calculations reveal that the introduction of Fe significantly decreases the formation energy of parallel steps on sapphire surfaces and contributes to the edge-nucleation of unidirectional TMDCs domains (>99%). The ultrahigh electron mobility (~86 cm2 V -1 s-1) and remarkable on/off current ratio (~108) are discovered on 4-inch single-crystal Fe-MoS2 monolayers due to the ultralow contact resistance and perfect Ohmic contact with metal electrodes. This work represents a substantial leap in terms of bridging the synthesis and doping of wafer-scale single-crystal 2D semiconductors without the need for substrate miscut, which should promote the further device downscaling and extension of Moore's law.