Tuning electronic properties of epitaxial multilayer-graphene/4H–SiC(0001) by Joule heating decomposition in hydrogen. (February 2020) - Sun, Cunzhi
Abstract: On the semi-insulating 4H–SiC (0001) surface, hydrogenated multilayers graphene (MLG) were epitaxially prepared by the method of Joule heating decomposition in the hydrogen atmosphere. The structural and chemical characteristics of multilayers graphene have been elaborately analyzed by the X-ray photoelectron and Raman spectroscopies, showing the level of hydrogenation being promoted with the increase of hydrogen pressure. Then, diodes with MLG/4H–SiC contact were fabricated and studied, proving that the Schottky barrier height (SBH) of MLG/4H–SiC junction was enhanced by the hydrogenation. By studying the typical current-voltage characteristics, the SBH was observed to be heightened from 0.84 eV to 1.0 eV along with the hydrogen pressure increasing from 10 −2 mbar to 10 2 mbar. Finally, graphene-semiconductor-graphene photodetectors were fabricated, showing peak responsivity as high as~ 0.9 A/W and external quantum efficiency of 345%, under the 324 nm illumination and biased at 3V. Graphical abstract: Image 1 Highlights: A Joule heating decompostion method has been employed. Bandgap of epitaxial multilayers graphene could be opened and modulated by different level of hydrogenation. Schottky barrier height as high as a 1.0 eV have been achieved at the 10 2 mbar hydrogen pressure.