Fabrication And Performance Research Of Thin Film Transistor Based On Dispersed CNT Solution

Due to the easy access to obtain high purity semiconducting carbon nanotube, the method of "deposition from solution" has some special advantages over other methods in fabricating CNT field effect transistors (FET), especially when we fabricate thin film transistors with high on-off ratio in flexible transparent electronic circuits. To increase the carrier mobility and improve the time response of the devices, the channel length has to be shortened, which brings about the problem of controlled deposition of single carbon nanotube. Moreover, carbon nanotube FET also faces the challenges of polarity control, increasing environmental stability, reducing the hysteresis and so on.We started with the dispersing of carbon nanotube in organic solution, and then we tried to deposit carbon nanotube on various substrates with controlled density. We also carried out some tasks about both position and direction controlled deposition of carbon nanotube. To guarantee the quality of carbon nanotube in future application of transistor, we carefully characterized carbon nanotube parameters, including the mean diameter, length distribution and the proportion of semiconducting nanotubes.To improve the performance of FET, all the factors that affect should be studied carefully, so we looked into some effects like oxygen absorption and desorption, different contact metal, gate length and dielectric materials. Because of the device’s extremely sensitivity to oxygen, in some cases desorption of oxygen and passivation of the devices became very important, and we found that this could be fulfilled by atomic layer deposition (ALD) of Al2O3or oxidation of evaporated Yttrium or Aluminum.In the end of this dissertation, we demonstrated some circuit applications of our devices, including inverter, NAND and NOR gate, ring oscillator and so on. Particularly the ring oscillator gives us a direct view of the time response of our devices and offers us an enlightenment to further improve the device performance.