Gigahertz frequency mixing and multiplication in an all-van der Waals ambipolar MoTe2 transistor

Gigahertz frequency mixing and multiplication are demonstrated in ambipolar few-layer MoTe2 transistors based on all-van der Waals architecture. The devices combine few-layer MoTe2 channels with graphene electrodes and hexagonal boron nitride dielectric/encapsulation layers, reducing contact-induced disorder and Fermi-level pinning while preserving symmetric ambipolar transport. Lateral and vertical transistor geometries exhibit V-shaped transfer characteristics with high current modulation, including ION/IOFF ratios exceeding 105. When biased near the charge-neutrality point, the nonlinear ambipolar response enables radio frequency mixing and harmonic generation under gigahertz excitation. In the lateral device, a 1 GHz input produces clearly resolved harmonics up to the eighth order, while vertical devices also show strong nonlinear frequency conversion. To evaluate mechanical robustness, the same van der Waals design is implemented on a flexible Kapton substrate. The flexible transistor retains ambipolar transport and demonstrates robust nonlinear radio frequency functionality under bending, indicating that the device functionality is preserved under moderate mechanical strain. These results establish all-van der Waals MoTe2 transistors as compact and mechanically adaptable building blocks for high-frequency analog signal-processing applications.