Pramanik Arindam, Thakur Sangeeta, Singh Bahadur, Willke Philip, Wenderoth Martin, Hofsäss Hans, Di Santo Giovanni, Petaccia Luca, Maiti Kalobaran
Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India.
Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149 Trieste, Italy.
Phys Rev Lett. 2022 Apr 22;128(16):166401. doi: 10.1103/PhysRevLett.128.166401.
We study the properties of the Dirac states in SiC-graphene and its hole-doped compositions employing angle-resolved photoemission spectroscopy and density functional theory. The symmetry-selective measurements for the Dirac bands reveal their linearly dispersive behavior across the Dirac point which was termed as the anomalous region in earlier studies. No gap is observed even after boron substitution that reduced the carrier concentration significantly from 3.7×10^{13} cm^{-2} in SiC-graphene to 0.8×10^{13} cm^{-2} (5% doping). The anomalies at the Dirac point are attributed to the spectral width arising from the lifetime and momentum broadening in the experiments. The substitution of boron at the graphitic sites leads to a band renormalization and a shift of the Dirac point towards the Fermi level. The internal symmetries appear to be preserved in SiC-graphene even after significant boron substitutions. These results suggest that SiC-graphene is a good platform to realize exotic science as well as advanced technology where the carrier properties like concentration, mobility, etc., can be tuned keeping the Dirac fermionic properties protected.
我们采用角分辨光电子能谱和密度泛函理论研究了碳化硅-石墨烯及其空穴掺杂组合物中狄拉克态的性质。对狄拉克能带的对称选择性测量揭示了它们在狄拉克点附近的线性色散行为，在早期研究中该区域被称为异常区域。即使在硼取代后，载流子浓度从碳化硅-石墨烯中的3.7×10¹³ cm⁻²显著降低至0.8×10¹³ cm⁻²（5%掺杂），也未观察到能隙。狄拉克点处的异常归因于实验中由寿命和动量展宽引起的谱线宽度。在石墨位点上硼的取代导致能带重整化以及狄拉克点向费米能级移动。即使在大量硼取代后，碳化硅-石墨烯中的内部对称性似乎仍得以保留。这些结果表明，碳化硅-石墨烯是实现奇异科学以及先进技术的良好平台，在该平台中，可以在保护狄拉克费米子特性的同时调节诸如浓度、迁移率等载流子特性。
