Kazuhiro Kanda

Abstract The development of controllable doping and reduction techniques for graphene oxide (GO) is essential for the fabrication of high-performance, graphene-based electronic devices. In particular, achieving stable n-type graphene remains a key challenge in the realization of complementary graphene circuits. In this study, we present a novel method for the simultaneous reduction and nitrogen doping of GO using atomic hydrogen and atomic nitrogen (AHAN). X-ray photoelectron spectroscopy confirmed that GO films were effectively reduced by soft X-ray irradiation followed by AHAN treatment. Notably, samples subjected to soft X-ray irradiation prior to AHAN treatment exhibited lower electrical resistance, indicating that defect formation induced by X-rays facilitates enhanced nitrogen incorporation during the subsequent AHAN process. These results demonstrate the potential of the AHAN treatment as a promising strategy for the controlled synthesis of n-type graphene, contributing to the advancement of graphene-based electronic and thermoelectric applications.

Abstract X-ray lithography was performed using synchrotron radiation to fabricate a nozzle array filter with submicron-order aperture diameters for a mesh nebulizer, as generating mist with a high yield of submicron-sized droplets is essential for delivering medication deep into the lungs. Utilizing polymethylmethacrylate as the resist material, precise control of X-ray exposure with distribution was performed to achieve submicron-order aperture fabrication, using a two-axis lead zirconate titanate stage with nanometer-scale positioning resolution. By precisely controlling the exposure process and development time on a minute scale, we successfully fabricated a nozzle array with submicron-order aperture diameters.