Sarker Biddut K, Cazalas Edward, Chung Ting-Fung, Childres Isaac, Jovanovic Igor, Chen Yong P
Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.
Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
Nat Nanotechnol. 2017 Jul;12(7):668-674. doi: 10.1038/nnano.2017.46. Epub 2017 Apr 10.
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.
石墨烯非凡的光学和电学特性使其成为高性能光电探测器的一个有前途的组件。然而，在迄今为止展示的典型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位置，其覆盖面积远小于器件尺寸。对于许多光电器件应用而言，期望在大得多的面积上获得光响应和位置灵敏度。在此，我们通过在背栅石墨烯场效应晶体管（GFET）上扫描聚焦激光束，报告了碳化硅（SiC）衬底上背栅石墨烯场效应晶体管中光响应的空间依赖性。即使在距石墨烯大于500 µm的距离处照射SiC衬底，该GFET仍显示出非局部光响应。根据光照位置，光响应度和光电流可变化超过一个数量级。我们的观察结果通过基于衬底中光激发载流子电荷传输的数值模型进行了解释。
