Terahertz Devices With Carbon Nanotube Cathode Array Of Research

THz source based on the vacuum electronics can generate THz wave very effectively. The cathode plays a most important role in the vacuum THz device. At present, the thermal cathode is hard to adapt to the structure requirement of vacuum THz devices, especially the low power THz device with power of μW to W, the requirements on volume is so strict that thermal cathode can’t meet the requirement. Field emission cathode would be the best choice to be the vacuum THz devices cathode due to its unique advantages such as low temperature, small volume and high starting speed and so on. In this paper, the carbon nanotube arrays will be grown according to the requirement of terahertz devices so that they can be applied in the terahertz devices.The following contents is studied in this paper:(1) Explore the growth process of carbon nanotube arrays. In this paper, the different growth conditions is studied which affect the morphology of carbon nanotube array, meanwhile the different catalyst layer structures are also studied. The carbon nanotube arrays would have the best morphology and adhesion to the substrate when produced by Cu/Al/Fe catalyst structure.(2) The improvement of treatment process. The carbon nanotube sample was annealed before field emission test. The results shows that carbon nanotubes present more tighten with the substrate, after being treated at the temperature of790℃.(3) Design and preparation of the carbon nanotube array gate structure.A kind of outside gate cathode component model is designed in this paper and simulated by electromagnetic particle simulation software in order to apply CNT FEA into low-power and small-scale THz devices.(4) The results of the field emission test show that the current density of carbon nanotube arrays can achieve1.9A/cm2with a total emission current of60mA.