Carbon And Nitrogen Nano Cone Membrane Preparation And Properties Research

Vertically aligned carbon nitride nanocone (CNNC) arrays were prepared on Ni-covered (100) silicon wafers by abnormal glow discharge plasma assisted chemical vapor deposition method (GPCVD) and pulsed laser deposition (PLD) in this thesis. The prepared carbon nitride nanocone arrays were characterized; based on the characterization of the as-grown thin films and the analysis of the growth environments, the effects of the experimental conditions on the growth of CNNC arrays were studied and their growth mechanism was discussed; and we discussed the electrical and optical properties of the carbon nitride nanocone films. At appropriate experimental conditions, vertically aligned CNNC arrays with intact cone-shapes, β-C3N4microstructures and tip curvature diameters of only3-4nm could be fabricated. This kind of CNNC arrays have many potential applications, such as tips for microscopes, electron-emitting units in field-emission-displays, electron-capture electrodes of solar cells etc..An abnormal glow discharge plasma assisted chemical vapor deposition method (GPCVD) can produce plasma with high density, high degree of ionization by gas discharge at low working pressures, in order to enhance the chemical reactions and reduce the temperature of the substrate, it can prepare carbon nitride thin films and nanocone arrays at low temperature condition. Pulsed laser deposition (PLD) is a technique of using pulse laser ablation on the target, then the ablation materials deposited on the different substrates as the form of thin films, which is particularly suitable for preparation of the refractory compound thin films.The investigation in this thesis comprises two sections as follows:(1) Carbon nitride nancone films preparation:using direct current abnormal glow discharge plasma chemical vapor deposition method vertically aligned carbon nitride nanocone arrays were prepared on Ni-covered (100) silicon wafers. Nanocone’s morphology、composition、structure、crystallinity and distribution depends on the variety experimental conditions, the experiment mainly from the choice of substrate, gas discharge choosing, discharge gas flow ratio and discharge tip-substrate distance factors to study, find the ideal conditions for preparing good morphology and crystalline nanocone arrays.(2) Carbon nitride nanocone characterization and performance characteristics: through a variety of methods of analysis and testing characterizes the synthesis of CNNC array mainly in scanning electron microscopy (FESEM)、transmission electron microscopy (TEM)、selected-area electron diffraction (SAED), X ray photoelectron spectroscopy (XPS). Based on the transmission electron microscopy and diffraction microscopy the CNNCs are mainly of crystallinity β-C3N4structure, The [N]/[C] atomic ratio in this sample is about0.64from the XPS, the contents of sp3-N-C, sp2-N-C and N=N or N=O bondings are57.2%,36.3%and6.5%, respectively, it can be inferred that the more C atoms contained in the as-grown CNNCs are bonded with N atoms, while most of the contained N atoms are bonded with C atoms into sp3-hybridized N-C bondings. The synthesized nanocone arrays have high nitrogen content and extremely small tip curvature radius. The studies of film features are mainly from the electrical and optical properties, electrical measurements show that nanocone arrays have good electrical conductivity, the resistivity of single nanocone is about1.6×10-3Ω·m. The absorption spectrum of films from300to800nm displays the high absorption rate at the band, in partial ultraviolet the absorption rate is the highest, the absorption rate decreased gradually to the infrared band. The film determined by the morphology、electrical and optical properties of carbon nitrogen nanocone array as the electron transport layer is helpful for improving polymer/inorganic composite thin film solar cells’ exciton generation rate、exciton charge separation rate and electron transmission efficiency.The experiment of DC plasma deposition method to synthesize carbon nitride nanocone is easy to observe the discharge process and thin film deposition in the quartz tube, so we can adjust and control the film growth process easily, at the same time the substrate temperature is higher and the body temperature is low, it greatly reduce the damage and pollution to substrate by high temperature. The method of synthesizing carbon nitride nanocone arrays has a good application prospect in the high efficiency solar cells’ electron-capture electrodes and electron-emitting units in field-emission-displays.