The extraordinary optical and electronic properties of graphene make it a promising component of high-performance photodetectors. However, in typical graphene-based photodetectors demonstrated to date, the photoresponse only comes from specific locations near graphene over an area much smaller than the device size. For many optoelectronic device applications, it is desirable to obtain the photoresponse and positional sensitivity over a much larger area. Here, we report the spatial dependence of the photoresponse in backgated graphene field-effect transistors (GFET) on silicon carbide (SiC) substrates by scanning a focused laser beam across the GFET. The GFET shows a nonlocal photoresponse even when the SiC substrate is illuminated at distances greater than 500 µm from the graphene. The photoresponsivity and photocurrent can be varied by more than one order of magnitude depending on the illumination position. Our observations are explained with a numerical model based on charge transport of photoexcited carriers in the substrate.

中文翻译：

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SiC上具有微米级石墨烯的光电晶体管的位置相关和毫米范围的光电检测

石墨烯的非凡光学和电子特性使其成为高性能光电探测器的有希望的组成部分。但是，在迄今为止展示的典型的基于石墨烯的光电探测器中，光响应仅来自石墨烯附近特定区域，且其位置远小于器件尺寸。对于许多光电设备应用，期望在更大的区域上获得光响应和位置灵敏度。在这里，我们通过扫描聚焦的激光束穿过GFET来报告碳化硅（SiC）衬底上的背向石墨烯场效应晶体管（GFET）中的光响应的空间依赖性。即使在距石墨烯大于500 µm的距离照射SiC衬底时，GFET仍显示出非局部光响应。光响应度和光电流可以根据照明位置而变化一个以上数量级。我们的观察结果是基于基于光激发载流子在基底中的电荷传输的数值模型来解释的。