Breaking Barriers: Centimeter-Sized Single Layer WSe2 by Gold-Mediated Exfoliation for Ambipolar Field Effect Transistors at Ultra-Low Voltages

Transition Metal Dichalcogenides (TMDCs) are promising semiconductor alternatives to silicon in CMOS technology. Their layered nature allows scaling to a single layer (1L) without degrading electrical performance, enabling further miniaturization of field-effect transistors (FETs). TMDCs like WSe₂ exhibit ambipolar transport, allowing fabrication of both p-type and n-type devices on a single flake, simplifying circuit design. Ambipolar, large-area, high-quality 1L-WSe₂ is therefore highly desirable. Here, centimeter-scale exfoliated 1L-WSe₂ is achieved, reaching 1L areas of up to 20 mm² via thermally activated gold-mediated TMDC exfoliation using large, high-quality WSe₂ parent crystals. The quality of 1L-WSe2 is comprehensively investigated via Raman spectroscopy, photoluminescence, X-ray, and ultraviolet photoelectron spectroscopy, as well as electronic transport measurements. For the latter, 1L-WSe₂-based FETs are fabricated on lithium-ion conducting glass ceramic substrates serving as both supporting substrate and high-performance gate. Subthreshold slopes as steep as 30 and 50 mV dec⁻¹, maximum mobilities of 15 and 18 cm² V⁻¹ s⁻¹, and ON/OFF ratios of ≈10⁸ and 10⁹ for electron and hole currents, respectively, are achieved at ultra-low gate voltages (≈2 V). The performance, demonstrated across 15 devices, suggests that 1L-WSe₂ in this device architecture can pave the way toward providing an alternative to conventional silicon-based CMOS technology for innovative, further miniaturized devices.