Polarity-dependent twist-controlled resonant tunneling device based on few-layer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">W</mml:mi><mml:msub><mml:mi>Se</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Kei Kinoshita, Rai Moriya, Shota Okazaki, Yijin Zhang, Satoru Masubuchi, Kenji Watanabe, Takashi Taniguchi, T. Sasagawa, Tomoki Machida
Abstract
Few-layer (FL) transition metal dichalcogenides have been found to exhibit discrete subbands, called van der Waals quantum well (vdWQW) states, resulting from out-of-plane quantum confinement. In this study, we reveal the twisted-resonant tunneling characteristics of a vdWQW device using a three-layer (3L) $\mathrm{W}{\mathrm{Se}}_{2}/h$-BN/3L-$\mathrm{W}{\mathrm{Se}}_{2}$ junction with different twist angles ${\ensuremath{\theta}}_{\mathrm{tunnel}}$ between the two 3L $\mathrm{W}{\mathrm{Se}}_{2}$ flakes. Using an ambipolar graphene contact to $\mathrm{W}{\mathrm{Se}}_{2}$, two primary vdWQW states of 3L $\mathrm{W}{\mathrm{Se}}_{2}$ located in the conduction band (CB) and valence band (VB) were investigated. We found that while the current peak positions due to the electron resonant tunneling between the CB-QW states significantly change with ${\ensuremath{\theta}}_{\mathrm{tunnel}}$ having a periodicity of ${60}^{\ensuremath{\circ}}$, the hole resonant tunneling between the VB-QW states exhibits no ${\ensuremath{\theta}}_{\mathrm{tunnel}}$ dependence; these are due to different angular dispersions of two vdWQWs. The results highlight the different twistronic properties of CB and VB vdWQWs in FL $\mathrm{W}{\mathrm{Se}}_{2}$.