Effects of plasma and gas flow conditions on the structures and photoluminescence of carbon nanomaterials

Abstract

In this work, we demonstrate the conversion of amorphous to crystalline carbon nanomaterials through the synthesis of carbon nanomaterials on silicon substrates coated with gold films in CH4-N2-H2 environment and CH4-N2-H2 plasma by hot filament chemical vapor deposition, respectively. The characterization results indicate that the flow rate of methane and plasma lead to the structural conversion and the change of composition of carbon nanomaterials, which are related to the conversion of hydrocarbon radicals to benzene molecules on the gold nanoparticles and the incorporation of nitrogen in the carbon nanomaterials caused by the plasma. Furthermore, the isothermal absorption theory was applied to study the structural conversion of amorphous to crystalline carbon nanomaterials in the CH4-N2-H2 plasma. The studies suggest that the change of surface tension caused by the dissolution of different carbon species in gold nanoparticles plays a key role for the structural conversion of the carbon nanomaterials. The photoluminescence properties of synthesized carbon nanomaterials were investigated at room temperature. The results exhibit that the carbon nanomaterials can generate the ultraviolet, blue, green and red light due to the functional groups on the surfaces of carbon nanomaterials and they are expected to emit white light after the functional groups are adjusted. The outcomes of this work are significant to control the structures of carbon nanomaterials and contribute the development of white light emission devices.