Resonant Tunneling between Quantized Subbands in van der Waals Double Quantum Well Structure Based on Few-Layer WSe<sub>2</sub>.

Kinoshita, Kei; Moriya, Rai; Okazaki, Shota; Zhang, Yijin; Masubuchi, Satoru; Watanabe, Kenji; Taniguchi, Takashi; Sasagawa, Takao et al. · Nano Lett · 2022

basic_science · Level V

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Abstract

We demonstrate van der Waals double quantum well (vDQW) devices based on few-layer WSe<sub>2</sub> quantum wells and a few-layer <i>h</i>-BN tunnel barrier. Due to the strong out-of-plane confinement, an exfoliated WSe<sub>2</sub> exhibits quantized subband states at the Γ point in its valence band. Here, we report resonant tunneling and negative differential resistance in vDQW at room temperature owing to momentum- and energy-conserved tunneling between the quantized subbands in each well. Compared to single quantum well (QW) devices with only one QW layer possessing quantized subbands, superior current peak-to-valley ratios were obtained for the DQWs. Our findings suggest a new direction for utilizing few-layer-thick transition metal dichalcogenides in subband QW devices, bridging the gap between two-dimensional materials and state-of-the-art semiconductor QW electronics.