Photoluminescence from carbon structures grown by inductively coupled plasma chemical vapor deposition

Carbon micro/nanostructures were grown by inductively coupled plasma chemical vapor deposition (ICP-CVD) at low pressure into a tubular reactor under pure methane and using substrates of SAE 304 stainless steel. The samples show diverse structures and properties depending on the position inside the quartz tube, due to the different temperatures and environmental conditions. In this experiment, the authors have obtained structures with different scales (micro and nano), depending on the growing temperature and the position inside the reactor. Carbon microstructures were obtained on the extreme parts of the tubular reactor at low temperatures. In contrast, carbon nanostructures appeared after the plasma resonator at temperatures higher than 700 degrees C. X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry evidenced functional groups with hydrogen and oxygen atoms except for nanostructures at 750 degrees C showing vertical carbon nanowalls with more than ten crystalline layers, such as it was verified by field emission SEM, TEM, and Raman shift spectroscopy. An intense photoluminescence in the visible range was revealed from the samples excited by laser (325nm), except the nanowall samples, which exhibited a poor photoluminescence. The purpose of this work is to study the photoluminescence of carbon structures produced by ICP-CVD and to evidence the role of hydrogen and oxygen functional groups with hydrogen and oxygen atoms. The understanding of these processes provides additional criteria for designing new materials based on carbon, which is environmentally friendly, for application to luminescent devices.