Resonant Tunneling in WSe₂/<i>h</i>-BN/WSe₂/<i>h</i>-BN/WSe₂ van der Waals Triple Quantum Well Device

Recent advancements in van der Waals quantum well (vdW QW) structures using few-layer transition metal dichalcogenides have led to resonant tunneling devices with substantial negative differential resistance. The performance of these devices, comparable to that of state-of-the-art III-V semiconductor QW devices, suggests that incorporating vdW QW with sophisticated vdW stacking methodologies could lead to innovative quantum devices. In this research, we realize vertical tunneling in a vdW triple QW (TQW) device of trilayer (3L) -WSe₂/<i>h</i>-BN/3L-WSe₂/<i>h</i>-BN/3L-WSe₂. The three-level subbands formed in the 3L WSe₂ function as a vdW QW, and the few-layer-thick <i>h</i>-BN acts as a tunnel barrier. Applying a bias between the first and third QWs enables control of the subband resonant tunneling between QWs. The fabricated TQW exhibits five resonant tunneling peaks accompanying a negative differential resistance in the current-voltage characteristics. This is in stark contrast to the double QW, in which only three resonant tunneling peaks are observed. This phenomenon can be attributed to the multiplication of resonant tunneling, originating from the avoided coincidence of resonant tunneling at the first and second tunnel barriers. Our results illustrate the potential of multiple vdW QWs for enhancing the performance of optoelectronic and logic devices.