Graphene photodetectors with ultra-broadband and high responsivity at room temperature
Graphene photodetectors with ultra-broadband and high responsivity at room temperature
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DOI：
10.1038/nnano.2014.31
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发表时间：
2014-04-01
影响因子：
38.3
通讯作者：
Zhong, Zhaohui
中科院分区：
文献类型：
--
作者：
Liu, Chang-Hua;Chang, You-Chia;Zhong, Zhaohui
在宽光谱范围内检测光的能力是成像、传感、光谱和通信（1，2）中的几种技术应用的核心。石墨烯是超宽带光电探测器的一种有前途的候选材料，因为它的吸收光谱覆盖了整个紫外到远红外范围（3，4）。然而，由于单层碳原子的小的光学吸收，基于石墨烯的光电探测器的响应度到目前为止被限制为数十mAW（-1）（参考文献5-10）。在光吸收层中集成胶体量子点可以将石墨烯光电探测器的响应度提高到类似于1 × 10（7）AW（-1）（参考文献11），但是光电探测的光谱范围减小，因为光吸收发生在量子点中。在这里，我们报告了一个超宽带光电探测器设计的基础上，石墨烯双层异质结构。检测器是由一对堆叠的石墨烯单层（顶层，栅极;底层，沟道）组成的光电晶体管，所述石墨烯单层由薄隧道势垒分离。在光照射下，在顶层中产生的光激发的热载流子隧穿到底层中，导致在栅极上的电荷积累和对沟道电导的强烈的光电门效应。这些器件展示了从可见光到中红外范围的室温光电探测，中红外响应度高于1 AW（-1），符合大多数应用的要求（12）。这些结果解决了宽带红外探测器的关键挑战，并有望为石墨烯基热载流子光电应用的发展。
The ability to detect light over a broad spectral range is central to several technological applications in imaging, sensing, spec-troscopy and communication(1,2). Graphene is a promising candidate material for ultra-broadband photodetectors, as its absorption spectrum covers the entire ultraviolet to far-infrared range(3,4). However, the responsivity of graphene-based photodetectors has so far been limited to tens of mAW(-1) (refs 5-10) due to the small optical absorption of a monolayer of carbon atoms. Integration of colloidal quantum dots in the light absorption layer can improve the responsivity of graphene photodetectors to similar to 1 x 10(7) AW(-1) (ref. 11), but the spectral range of photodetection is reduced because light absorption occurs in the quantum dots. Here, we report an ultra-broadband photodetector design based on a graphene double-layer hetero-structure. The detector is a phototransistor consisting of a pair of stacked graphene monolayers (top layer, gate; bottom layer, channel) separated by a thin tunnel barrier. Under optical illumination, photoexcited hot carriers generated in the top layer tunnel into the bottom layer, leading to a charge build-up on the gate and a strong photogating effect on the channel conductance. The devices demonstrated room-temperature photodetection from the visible to the mid-infrared range, with mid-infrared responsivity higher than 1 AW(-1), as required by most applications(12). These results address key challenges for broadband infrared detectors, and are promising for the development of graphene-based hot-carrier optoelectronic applications.