Adolfo De Sanctis: Extraordinary linear dynamic range in laser-defined functionalized graphene photodetectors

posted 14 Jun 2017, 00:51 by Peter Boggild
Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, EX4 4QL Exeter, UK

Graphene-based photodetectors have demonstrated mechanical flexibility, large operating bandwidth, and broadband spectral response [1]. However, their linear dynamic range (LDR) is limited by graphene’s intrinsic hot-carrier dynamics, which causes deviation from a linear photoresponse at low incident powers. At the same time, multiplication of hot carriers causes the photoactive region to be smeared over distances of a few micrometers, limiting the use of graphene in high-resolution applications [2]. We present a novel method for engineering photoactive junctions in FeCl3-intercalated graphene using laser irradiation. Photocurrent measured at these planar junctions shows an extraordinary linear response with a linear dynamic range (LDR) value of 44 dB, at least 4500 times larger than that of other graphene, while maintaining high stability against environmental contamination without the need for encapsulation. The observed photoresponse is purely photovoltaic, demonstrating complete quenching of hot-carrier effects. These results pave the way toward the design of ultrathin photodetectors with unprecedented LDR for high-definition imaging and sensing in extreme environments.

1. F. H. L. Koppens et al. Photodetectors based on graphene, other two-dimensional materials and hybrid systems. Nat. Nanotechnol. 9, 780 (2014);
2. J. C. W. Song et al. Hot carrier transport and photocurrent response in graphene. Nano Lett. 11, 4688 (2011);

Adolfo De Sanctis is currently Research Fellow in the Quantum Systems and Nanomaterials group at the University of Exeter (UK). He received his Ph.D. from the University of Exeter, with a dissertation on "Manipulating light in two-dimensional layered materials" in December 2016. He previously obtained a M.Sc. in Applied physics and Nanotechnology in University of L'Aquila, Italy, with a dissertation on "Growth and Characterization of Graphene" (Dec 2013). His research activity focuses on the interaction of light with 2D materials. In collaboration with ICFO, The Institute of Photonic Sciences in Barcelona (Spain), he studies the use of chemically functionalized graphene for opto-electronic applications, ranging from transparent and flexible electrodes to atomically-thin photodetectors. Adolfo also designed and built several experimental instruments used in his research. He is active in the field of Outreach and Scientific Communication through personal projects and collaborations.