N-Doped graphene glass was prepared through a novel plasma-assisted HFCVD approach, which exhibited significantly enhanced voltage generation for energy harvesting.

Direct growth of graphene films on glass is of great importance but has so far met with limited success. The noncatalytic property of glass results in the low decomposition ability of hydrocarbon precursors, especially at reduced temperatures (<1000 °C), and therefore amorphous carbon (a-C) films are more likely to be obtained. Here, we report the hydrogen influence on the structural and electrical properties of carbon films deposited on quartz glass at 850 °C by hot-filament chemical vapor deposition (HFCVD). The results revealed that the obtained a-C films were all graphitelike carbon films. Structural transition of the deposited films from a-C to nanocrystalline graphene was achieved by raising the hydrogen dilution ratios from 10 to over 80%. On the basis of systematic structural and chemical characterizations, a schematic process with three steps including sp chain aggregation, aromatic ring formation, and sp bond etching was proposed to interpret the structural evolution. The nanocrystalline graphene films grown on glass by HFCVD exhibited good electrical performance with a carrier mobility of 36.76 cm/(V s) and a resistivity of 5.24 × 10 Ω cm over an area of 1 cm. Temperature-dependent electrical characterizations revealed that the electronic transport in carbon films was dominated by defect, localized, and extended states, respectively, when increasing the temperature from 75 to 292 K. The nanocrystalline graphene films presented higher carrier mobility and lower carrier concentration than those of a-C films, which was mainly attributed to their smaller conductive activation energy. The present investigation provides an effective way for direct growth of graphene films on glass at reduced temperatures and also offers useful insights into the understanding of structural and electrical relationship between a-C and graphene.

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Amorphous carbon (a-C) films were prepared by e-beam evaporation on silicon substrates. The effects of substrate temperature between room temperature and 600 C were mainly studied. Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV-Vis-NIR and Hall-effect measurements were used to characterize the structure, morphology, roughness, transmittance and conductivity of a-C films, respectively. The results indicated the films obtained by e-beam evaporation were all graphite-like carbon films. The films deposited at 200 C with a thickness of 75 nm presented the best performance with I D /I G of 4.50, FWHM G of 115.9 cm À1 , an optical gap of 0.6 eV, a roughness of 0.825 nm and an electrical resistivity of 3.60 Â 10 À3 U cm. As the thickness reduced to about 8 nm while remaining at the same substrate temperature, the films still exhibited good structural quality, continuity and conductivity.