Substrate Doping Effect and Unusually Large Angle van Hove Singularity Evolution in Twisted Bi‐ and Multilayer Graphene

• DOI: 10.1002/adma.201606741
• Publication Date: 2017-05-08T12:26:42Z
• Authors: Han Peng; Niels B. M. Schröter; Jianbo Yin; Huan Wang; Ting‐Fung Chung; Haifeng Yang; Sandy Ekahana; Zhongkai Liu; Juan Jiang; Lexian Yang; Teng Zhang; Cheng Chen; Heng Ni; Alexey Barinov; Yong P. Chen; Zhongfan Liu; Hailin Peng; Yulin Chen
• Keywords: Van Hove singularity; Bilayer graphene; Fermi energy

Graphene has demonstrated great potential in new-generation electronic applications due to its unique properties such as large carrier Fermi velocity, ultrahigh mobility, and high material stability. Interestingly, the structures can be further engineered multilayer graphene by introduction of a twist angle between different layers create van Hove singularities (vHSs) at adjustable binding energy. In this work, using angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution, band their evolution are systematically studied bilayer trilayer sheets. A doping effect is directly observed system well vHSs over wide range angles (from 5° 31°) tunable energy 2 eV. addition, formation multiple (at energies) also graphene. The tuning vHS twisted provides promising base for optoelectrical broadband wavelength selectivity from infrared ultraviolet regime, an example application selective photodetector.