Giant intrinsic photoresponse in pristine graphene
Giant intrinsic photoresponse in pristine graphene
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DOI：
10.1038/s41565-018-0323-8
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发表时间：
2019-02-01
影响因子：
38.3
通讯作者：
Jarillo-Herrero, Pablo
中科院分区：
文献类型：
--
作者：
Ma, Qiong;Lui, Chun Hung;Jarillo-Herrero, Pablo
当费米能级与石墨烯的狄拉克点对齐时，减少的电荷屏蔽会极大地增强电子-电子散射(1-5)。在光激发系统中，狄拉克费米子中电子-电子散射的运动学预计会产生新的光电现象 (6-11)。在本文中，我们报告了对石墨烯中本征光电流的观察，该光电流发生在与之前在石墨烯中观察到的所有光热电或光伏光电流不同的参数范围（12-20）：光电流仅出现在电荷中性点，不需要有限掺杂。与在 p-n 或接触结附近增强的其他光电流类型不同，我们工作中观察到的光电流出现在边缘/角落附近。通过系统的数据分析，我们表明这种现象源于电荷中性石墨烯中独特的电子-电子散射运动学。我们的结果不仅强调了狄拉克费米子光电响应中有趣的电子动力学，而且还为基于本征、电荷中性狄拉克费米子的光电探测和能量收集应用提供了一种新方案。
When the Fermi level is aligned with the Dirac point of graphene, reduced charge screening greatly enhances electron-electron scattering(1-5). In an optically excited system, the kinematics of electron-electron scattering in Dirac fermions is predicted to give rise to novel optoelectronic phenomena(6-11). In this paper, we report on the observation of an intrinsic photocurrent in graphene, which occurs in a different parameter regime from all the previously observed photothermoelectric or photovoltaic photocurrents in graphene(12-20): the photocurrent emerges exclusively at the charge neutrality point, requiring no finite doping. Unlike other photocurrent types that are enhanced near p-n or contact junctions, the photocurrent observed in our work arises near the edges/corners. By systematic data analyses, we show that the phenomenon stems from the unique electron-electron scattering kinematics in charge-neutral graphene. Our results not only highlight the intriguing electron dynamics in the optoelectronic response of Dirac fermions, but also offer a new scheme for photodetection and energy harvesting applications based on intrinsic, charge-neutral Dirac fermions.