講演情報
[20p-A602-16]Chemically-tailored semiconductor moiré superlattices
〇Wenjin Zhang1, Zheng Liu2, Hiroshi Nakajo3,4, Soma Aoki3, Haonan Wan5, Yanlin Wang5, Yanlin Gao6, Mina Maruyama6, Takuto Kawakami7, Yasuyuki Makino1, Masahiko Kaneda1, Tongmin Chen8, Kohei Aso8, Tomoya Ogawa6,1, Takahiko Endo1, Yusuke Nakanishi1, Kenji Watanabe9, Takashi Taniguchi9, Yoshifumi Oshima8, Yukiko Yamada-Takamura8, Mikito Koshino7, Susumu Okada6, Kazunari Matsuda5, Toshiaki Kato3, Yasumitsu Miyata1 (1.Tokyo Metropolitan Uni., 2.AIST, 3.Tohoku Uni, 4.KOKUSAI ELECTRIC, 5.Kyoto Uni, 6.Uni. of Tsukuba, 7.Osaka Uni., 8.JAIST, 9.NIMS)
キーワード：
moire superlattices
The nanoscale periodic potential generated from moiré superlattices provides a new knob to tune and study the flat band effect and correlated physics. To date, moiré superlattices have been obtained using various two-dimensional (2D) materials, such as graphene, hexagonal boron nitride (hBN), transition metal dichalcogenides (TMDCs), and so on. In the 2D materials family, Janus monolayers of TMDCs have two different chalcogen atoms above and below the central metal atom. This asymmetric structure induced an out-of-plane electric field which provides an additional degree of freedom in moiré superlattices. Novel features in Janus materials were predicted by recent theoretical studies, such as: large Rashba spin–orbit coupling[1], piezoelectricity[2], and long-lived charge-transfer excitons[3]. Furthermore, recent calculations showed that excitons in Janus heterobilayer moiré superlattices are possible to realize high-temperature Bose–Einstein condensation state[3].
Although Janus TMDC monolayers and heterobilayers were obtained using thermal or plasma-assisted chemical reactions and transfer process[4,5], the experimental evidence of moiré superlattice and related excitonic properties in Janus heterobilayers are still unknown. Importantly, the small lattice mismatch between MX2 and MXY enables the formation of long-wavelength moiré superlattices, even from non-twisted bilayers in Janus heterobilayers. Therefore, direct preparation of Janus heterobilayers provides a scalable method for making moiré superlattices from MX2 bilayers. Here, we show experimental evidence for the formation of moiré superlattices and the associated excitonic responses in Janus heterobilayers of MoSSe/MoSe2 and WSSe/WSe2.
Although Janus TMDC monolayers and heterobilayers were obtained using thermal or plasma-assisted chemical reactions and transfer process[4,5], the experimental evidence of moiré superlattice and related excitonic properties in Janus heterobilayers are still unknown. Importantly, the small lattice mismatch between MX2 and MXY enables the formation of long-wavelength moiré superlattices, even from non-twisted bilayers in Janus heterobilayers. Therefore, direct preparation of Janus heterobilayers provides a scalable method for making moiré superlattices from MX2 bilayers. Here, we show experimental evidence for the formation of moiré superlattices and the associated excitonic responses in Janus heterobilayers of MoSSe/MoSe2 and WSSe/WSe2.