Laser Structuring of Graphene Oxide for PHOTOtronic SENSors and Nanoscale Characterization (PHOTOSENS)

• Applicants: Professorin Dr.-Ing. Olfa Kanoun; Professor Dr. Dietrich R. T. Zahn
• Subject Area: Synthesis and Properties of Functional Materials ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Microsystems
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 430426661

Due to its sensitivity to various measured variables, graphene oxide (GO) can be used to implement multifunctional sensors. Thereby, it has the decisive advantage of fast and easy fabrication as an ultrathin layer as it can be structured and functionalized by laser writing. By varying the laser parameters, the reduction degree can be adjusted to modify the electrical properties, such as the bandgap, in a defined way. The sensing properties can be adjusted to a certain quantity or to a certain measurement range.The main goal of this project is to investigate the possibility to tune the electronic properties i.e. work function and bandgap of GO layers by laser reduction in order to enhance their strain and photosensitivity. For this purpose, laser to realize in-plane heterostructures patterns GO films with thicknesses ranging from several nanometers to hundreds of nanometers. The electrodes will have tuned work functions and active channels with tuned electrical conductivities and bandgaps. Additionally, electrodes with different work functions can be realized as symmetric/asymmetric electrodes. For understanding the interaction of heterojunctions formed at the interface between electrodes and active channels, the energy level alignment and electron transport are investigated between differently prepared regions. To investigate the sensitivity to light and strain, Field-Effect-Transistor (FET) and Interdigitated Electrode (IDE) structures are realized by laser patterning of a GO layer on different substrates. The relation between applied strain, bandgap change of the active channel, and hence the sensitivity to light under strain are evaluated by means of electrical, optical, and topography characterizations. The miniaturization and the selectivity of laser patterning gives the ability to increase the sensitivity of sensors significantly. For example, the active channel bandgap can be adjusted to realize strain measurement in the small range and or to tune its electrical characteristics.

• DFG Programme: Research Grants