title: Position-dependent and millimetre-range photodetection in phototransistors with micrometre-scale graphene on SiC.
abstract: 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.
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.|Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Biddut K
authors.initials: BK
authors.lastname: Sarker
authors.affiliation: Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Edward
authors.identifier: 0000-0001-9703-8571
authors.initials: E
authors.lastname: Cazalas
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.|Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Ting-Fung
authors.identifier: 0000-0003-1359-4824
authors.initials: TF
authors.lastname: Chung
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.|Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Isaac
authors.initials: I
authors.lastname: Childres
authors.affiliation: Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.|Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Jovanovic
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.|Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.|School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA.|Purdue Quantum Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Yong P
authors.initials: YP
authors.lastname: Chen