2023-04-20 バッファロー大学(UB)
グラフェンは二次元材料であり、単層の厚さがあり、導電性があるため、単独では使いにくいが、ホウ素窒化物の2層間に挟むことで、「モアレ」模様が生じ、半導体のような性質を持つようになることが分かった。
この研究は、新しい通信デバイス、レーザー、発光ダイオードなどのテクノロジーアプリケーションに適していることを示している。
＜関連情報＞
- https://www.buffalo.edu/news/releases/2023/04/018.html
- https://www.nature.com/articles/s41467-023-37292-4
モアレ加工グラフェンのリエントラント金属状態および半導体状態におけるホットキャリアとホットフォノンのシグネチャー Signatures of hot carriers and hot phonons in the re-entrant metallic and semiconducting states of Moiré-gapped graphene
Jubin Nathawat,Ishiaka Mansaray,Kohei Sakanashi,Naoto Wada,Michael D. Randle,Shenchu Yin,Keke He,Nargess Arabchigavkani,Ripudaman Dixit,Bilal Barut,Miao Zhao,Harihara Ramamoorthy,Ratchanok Somphonsane,Gil-Ho Kim,Kenji Watanabe,Takashi Taniguchi,Nobuyuki Aoki,Jong E. Han &Jonathan P. Bird
Nature Communications Published:17 March 2023
DOI:https://doi.org/10.1038/s41467-023-37292-4
Abstract
Stacking of graphene with hexagonal boron nitride (h-BN) can dramatically modify its bands from their usual linear form, opening a series of narrow minigaps that are separated by wider minibands. While the resulting spectrum offers strong potential for use in functional (opto)electronic devices, a proper understanding of the dynamics of hot carriers in these bands is a prerequisite for such applications. In this work, we therefore apply a strategy of rapid electrical pulsing to drive carriers in graphene/h-BN heterostructures deep into the dissipative limit of strong electron-phonon coupling. By using electrical gating to move the chemical potential through the “Moiré bands”, we demonstrate a cyclical evolution between metallic and semiconducting states. This behavior is captured in a self-consistent model of non-equilibrium transport that considers the competition of electrically driven inter-band tunneling and hot-carrier scattering by strongly non-equilibrium phonons. Overall, our results demonstrate how a treatment of the dynamics of both hot carriers and hot phonons is essential to understanding the properties of functional graphene superlattices.
