论文标题
小扭角双层石墨烯中强烈的中红外光响应
Strong mid-infrared photoresponse in small-twist-angle bilayer graphene
论文作者
论文摘要
最近，由于其令人兴奋的物理特性，小扭反角（<2°）双层石墨烯受到了非凡的注意。与单层石墨烯相比，扭曲的双层石墨烯（TBG）中的布里渊区折叠会导致超晶格带隙的形成和状态密度的显着修饰。但是，这些新兴特性很少被利用用于实现新的光电设备。在这里，我们证明了5至12 um的中红外波长范围内的强，可调的光响应。当将1.81°TBG的费米水平调整为其超晶格带隙时，在12 um处达到了26 mA/w的最大外部光自我呼吸率。此外，强烈的光响应在很大程度上取决于超级晶状体带隙的形成，并且在无间隙的情况下以超巨大的扭曲角（<0.5°）消失。我们的演示揭示了TBG的有希望的光学特性，并为可调中红外光电子学提供了替代的材料平台。
Recently the small-twist-angle (< 2°) bilayer graphene has received extraordinary attentions due to its exciting physical properties. Compared with monolayer graphene, the Brillouin zone folding in twisted bilayer graphene (TBG) leads to the formation of superlattice bandgap and significant modification of density of states. However, these emerging properties have rarely been leveraged for the realization of new optoelectronic devices. Here we demonstrate the strong, gate-tunable photoresponse in mid-infrared wavelength range of 5 to 12 um. A maximum extrinsic photoresponsivity of 26 mA/W has been achieved at 12 um when the Fermi level in a 1.81° TBG is tuned to its superlattice bandgap. Moreover, the strong photoresponse critically depends on the formation of superlattice bandgap, and it vanishes in the gapless case with ultrasmall twist angle (< 0.5°). Our demonstration reveals the promising optical properties of TBG and provides an alternative material platform for tunable mid-infrared optoelectronics.
