Abstract
We have synthesized alignment and low turn-on electric field (~ 0.1 V/□m) one dimensional carbon nano-materials at 475-750 °C on silicon wafer and soda-lime glass by a microwave heated chemical vapor deposition. The growth properties are studied as a function of the deposition temperature, substrates, components, Ti interlayer, and growth mechanism. Moreover, the field emission properties of multiwall carbon nanotube (MWCNT) films with and without amorphous carbon nanowiers (a-CNWs) were investigated. It is found that the C-H bonding and adhesion are strongly related to the field emission characteristics of carbon nanotube emitters. The turn-on electronic field of 3.89 V/□m for pure MWCNT films and 0.11 V/□m for a-CNWs in MWCNT films were obtained. The experimental results indicated that the existence of hydrogenated amorphous carbon (a-C:H) nanowires have a low turn-on electronic field. The low turn-on electronic field significantly which can be attributed to the larger field enhancement effect due to the increase of hydrogen termination on the a-CNWs. By a more complete understanding of the role of MWCNTs and a-CNWs, a generic model for field emission from a-CNWs in MWCNT films can be developed. Our observation concerning the lower turn-on electronic field and high field enhancement factor (□) is explained in terms of a-C: H effect. The effect of titanium interlayer for different catalysts (palladium, nickel, cobalt) on growth and field emission properties of vertically aligned carbon nanotube was systematically studied by microwave heated chemical vapor deposition. It was found that the Ti interlayer has a strong affected on the multi-wall nanotube microstructure, alignment, morphology, adhesion, and field emission characteristics. The interlayer of titanium is shown to influence the growth characteristic with Ni or Co. The multi-wall carbon nanotubes catalyzed by Ni or Co have the best alignment and graphitization, whereas those from Pd are existed with amorphous carbon and nano-particles on the surface. The field emission results show the MWCNTs on Pd catalyst exhibited a lower turn-on field at 0.22 V/□m and a much higher emission current density of 2 mA/cm2 at 5 V/□m compared to Ni or Co catalyst, which exhibited 0.56 V/□m and 0.2 mA/cm2, 1.11 V/□m and 1.15 mA/cm2. From field emission measurement, the lowest turn-on field is about 0.22 V/□m and can be attributed C-H bonding in amorphous carbon. Based on microstructure characterization and field emission measurement, influence on interlayer of Ti from different catalysts is discussed. We have fabricated a high density carbon nanotube field emitter arrays (FEAs) on silicon and characterized its field emission properties. The CNT field emitter arrays were successfully fabricated in one square block (10 × 10 □m2) by photolithography process on chromium electrode for field emission display application. Field emission characterization has been performed on the diode and triode type CNT cathode at room temperature in high vacuum chamber below 2 × 10-5 torr. The interlayer (insulator) between cathode and gate is 1 □m thick thermal SiO2. Our high density CNT field emitter arrays emit 10 mA/cm2 at electric field of 3.75 V/□m, the gate voltage was maintained always below 10 V in triode emission device, which is one order of magnitude lower than any other results. Emission images also showed homogeneous emission from a diode CNT-FED at an anode voltage of 900 V, and the current reaches 0.1 mA ( ~ 2 mA/cm2). Our high density CNT-FEAs demonstrated that the well emission characterization with high brightness in diode emission device and low gate voltage in triode emission device. Moreover, the diode and triode type CNT-FED panel were fabricated using metal mesh, thin film process and standard photolithography technologies, furthermore the emission image and problems of display panel manufacture were obtained and discussed.