Negative differential resistance oscillators based on ReS₂/h-BN/ReS₂ van der Waals resonant tunneling diodes

Resonant tunneling diodes (RTDs) based on van der Waals (vdW) heterostructures show significant negative differential resistance (NDR), making them attractive for high-frequency device applications. In this study, we demonstrate an NDR oscillator using a 2L-ReS₂/h-BN/2L-ReS₂ vdW-RTD. The current−voltage (I−V) characteristics of the RTD exhibited sharp peaks accompanied by clear NDR. A large peak-to-valley current ratio of ~5.5 was achieved, indicating a high device performance. We attribute this high performance to the energy- and momentum-conserved resonant tunneling of electrons between the conduction band Γ points of the ReS₂. We constructed an LC oscillator using a vdW-RTD as the active element. When the RTD is biased into its NDR regime, it generates a stable oscillating voltage at room temperature. The oscillation frequency was tuned by varying inductance L, with a maximum frequency of ~0.52 MHz. This work represents the first demonstration of an NDR oscillator based on a ReS₂/h-BN/ReS₂ vdW-RTD, marking a significant step toward 2D material-based high-frequency electronic devices.