Comparative study of the carbon nanofilm and nanodots grown by plasma-enhanced hot filament chemical vapor deposition

Carbon nanofilm and nanodots were grown by plasma-enhanced hot filament chemical vapor deposition using methane, hydrogen and nitrogen as the reactive gases. The results of field emission scanning electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy indicate that the amorphous carbon nanofilm and nanodots are formed without and with nitrogen, respectively. The formation of carbon nanofilm and nanodots is the consequence of different sputtering-etching effects. The photoluminescence (PL) of carbon nanofilm and nanodots was studied in a SPEX 1403 Ramalog system using a 325 nm He-Cd laser as an excitation source and the PL spectra show the PL bands centered at about 411 and 513 nm for the carbon nanofilm and 405 and 504 nm for the carbon nanodots. Simultaneously, the PL results also indicate that the intensity of PL bands of carbon nanofilm is lower than that of carbon nanodots. The generation of different PL bands was interpreted by the transition mechanism. The difference in the intensity of PL bands is related to the size of carbon nanodots. The electron field emission (EFE) characteristics of carbon nanofilm and nanodots were investigated in a high-vacuum system. The results show that Fowler-Nordhelm curves are composed of two or three straight lines and the carbon nanofilm can emit a high current density, which originate from the diversification of carbon nanodots. The difference in the EFE results of carbon nanofilm and nanodots is associated to the size and number of carbon nanodots. These results can enrich our knowledge about carbon-based nanomaterials and are important to fabricate the carbon-based solid nanodevices in the field of optoelectronics. (C) 2014 Elsevier Ltd. All rights reserved.