Anomalous Photovoltaic Response of Graphene-on-GaN Schottky Photodiodes

Abstract

Graphene has attracted great attention as an alternative to conventional metallic or transparent conducting electrodes. Despite its similarities with conventional electrodes, recent studies have shown that a single-atom layer of graphene possesses unique characteristics, such as a tunable work function and transparencies for electric potential, reactivity, and wetting. Nevertheless, a systematic analysis of graphene and semiconductor junction characteristics has not yet been carried out. Here, we report the photoresponse characteristics of graphene-on-GaN Schottky junction photodiodes (Gr-GaN SJPDs), showing a typical rectifying behavior and distinct photovoltaic and photoelectric responses. Following the initial abrupt response to UV illumination, the Gr-GaN SJPDs exhibited a distinct difference in photocarrier dynamics depending on the applied bias voltage, which is characterized by either a negative or positive change in photocurrent with time. We propose underlying mechanisms for the anomalous photocarrier dynamics based on the interplay between electrostatic molecular interactions over the one-atom-thick graphene and GaN junction and trapped photocarriers at the defect states in the GaN thin film.

Improved Photoresponse of UV Photodetectors by the Incorporation of Plasmonic Nanoparticles on GaN Through the Resonant Coupling of Localized Surface Plasmon Resonance

“…For example, the Cu nanostructure/ZnO quantum dots hybrid architecture exhibited the ultrahigh UV photoresponsivity due to the enhanced plasmon scattering by the Cu nanostructures in the ZnO photoactive layer [15]. To date, various UV photodetectors have been demonstrated by the modification of nanoscale surface properties of photoactive materials, i.e., wide bandgap semiconductors of GaN, ZnO, TiO 2 , and SiC, as well as by the integration of advanced nanomaterials such as metallic nanoparticles (NPs), two-dimensional materials, and quantum dots [16][17][18][19][20]. For instance, the fabrication of heterostructures nanowires of semiconductors such as bicrystalline GaN, Al-doped ZnO/ZnO nanorings/PVK/PE-DOT:PSS and crystalline silicon/porous silicon have been realized for high UV photoresponsivity and fast response speed [21][22][23].…”

Preparation of hexagonal nanoporous Al2O3/TiO2/TiN as a novel photodetector with high efficiency

“…The desirable photodetector devices in industrial applications must have high performance include the fast response, high sensitivity, easy operation, and low 4 – 6 power consumption 7 . Many previous studies focused on the preparation of PD for light in the UV region depended on using photoactive materials that can work in these regions like GaN, ZnO, and SiC 8 , 9 . These materials can accept new properties for light detection through increasing the active sites in nanowires or nanotubes structures 10 , 11 .…”

Nanoporous TiN/TiO2/Alumina Membrane for Photoelectrochemical Hydrogen Production from Sewage Water

“…The working of the electrode can be carried out under direct sunlight or using another artificial light. Many semiconductor materials were used for the synthesis of the electrode, including oxides, sulfides, and some polymers [ 7 , 8 ]. The properties of the photocatalytic materials improve with increasing the active sites inside the materials, in which the nanowires or nanotube morphology increase the active sites through increasing the surface area of the materials [ 9 , 10 ].…”