Haider Golam, Ravindranath Rini, Chen Tzu-Pei, Roy Prathik, Roy Pradip Kumar, Cai Shu-Yi, Chang Huan-Tsung, Chen Yang-Fang
Department of Engineering and System Science, National TsingHua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan.
Nano-Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, No. 128, Section 2, Academia Rd, Nangang, Taipei, 11529, Taiwan.
Nat Commun. 2017 Aug 15;8(1):256. doi: 10.1038/s41467-017-00345-6.
The occurrence of zero effective mass of electrons at the vicinity of the Dirac point is expected to create new paradigms for scientific research and technological applications, but the related discoveries are rather limited. Here, we demonstrate that a simple architecture composed of graphene quantum dots sandwiched by graphene layers can exhibit several intriguing features, including the Dirac point induced ultralow-threshold laser, giant peak-to-valley ratio (PVR) with ultra-narrow spectra of negative differential resistance and quantum oscillations of current as well as light emission intensity. In particular, the threshold of only 12.4 nA cm is the lowest value ever reported on electrically driven lasers, and the PVR value of more than 100 also sets the highest record compared with all available reports on graphene-based devices. We show that all these intriguing phenomena can be interpreted based on the unique band structures of graphene quantum dots and graphene as well as resonant quantum tunneling.In graphene, electrons possess zero effective mass in proximity to the Dirac point, an unusual feature that could trigger the development of novel photonic devices. Here, the authors combine graphene quantum dots with two graphene layers and observe laser action with ultralow threshold.
在狄拉克点附近电子有效质量为零的情况有望为科学研究和技术应用创造新的范式，但相关发现相当有限。在此，我们证明由夹在石墨烯层之间的石墨烯量子点组成的简单结构可以展现出几个有趣的特性，包括狄拉克点诱导的超低阈值激光、具有超窄负微分电阻谱和电流以及发光强度量子振荡的巨大峰谷比（PVR）。特别地，仅12.4 nA cm的阈值是电驱动激光器所报道的最低值，并且超过100的PVR值与所有关于基于石墨烯的器件的现有报道相比也创下了最高记录。我们表明所有这些有趣的现象都可以基于石墨烯量子点和石墨烯独特的能带结构以及共振量子隧穿来解释。在石墨烯中，电子在狄拉克点附近具有零有效质量，这一不寻常的特性可能会引发新型光子器件的发展。在此，作者将石墨烯量子点与两个石墨烯层相结合，并观察到了具有超低阈值的激光作用。
