Abstract
Supercritical fluid owns the gas-like and liquid-like properties to extract matter from micro- and nano-structure without damage. In this paper, firstly, we apply the supercritical fluid technology to remove the moisture absorbed in carbon nanotube emitters. From experimental results, it is verified that the supercritical mixed with co-solvent could take moisture away operatively from carbon nanotubes at 50 °C, and the activated field carbon nanotubes have superior emission performance and electrical stability. Besides, the pressure of supercritical fluid would influence the efficiency of activating carbon nanotube emitters. Except extracting, it is allowed also for supercritical fluid to transport molecule into nano-structure. Therefore, we propose originally a low-temperature process for passivating traps by supercritical fluid. In our experiment, the supercritical fluid had delivered successfully the oxidants into sputter-deposited hafnium oxide layer to terminate traps at 150 °C. The material analyses report that the traps were passivated by oxidizing with oxidants. After the proposed treatment, the leakage current density of hafnium oxide is reduced significantly from 10-2 to 10-7 A/cm2, due to the conduction mechanism transformed from quantum tunneling to thermionic emission. The better capacitance-voltage curve and lower equivalent oxide thickness are achieved in addition.Next, the supercritical fluid technology is used to vary the traps density in band gap of electron-gun evaporation deposited silicon oxide films to produce the resistive switching memory material at 150 °C. The post-treated silicon oxide film exhibits superior dielectric characteristics and a resistive switching between high resistance state and low resistance state which is controlled by applied bias voltage. From experimental results, it is observed that the bistable resistance states are relative to the amount of traps. The silicon film with more traps would present lower voltages of switching resistance state and inferior retention property. Nevertheless, for the silicon film with fewer traps, the higher voltages of switching resistance state are required, and a longer retention property is achieved.Finally, the application of supercritical fluid technology on improving amorphous silicon thin film transistors is investigated. The transfer characteristics, such as off-current, density of states in middle gap of amorphous silicon, threshold voltage and subthreshold swing, have been enhanced by passivating Si dangling bonds.