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To improve the dielectric properties of sputter-deposited hafnium oxide (HfO2) films, the supercritical CO2 (SCCO2) fluid technology is introduced as a low temperature treatment. The ultrathin HfO2 films were deposited on p-type (100) silicon wafer by dc sputtering at room temperature and subsequently treated with SCCO2 fluids at 150°C to diminish the traps in the HfO2 films. After SCCO2 treatment, the interfacial parasitic oxide between the Si substrate and HfO2 layer is only about 5Å, and the oxygen content of the HfO2 films apparently increased. From current-voltage (I-V) and capacitance-voltage (C-V) measurements, the leakage current density of the SCCO2-treated HfO2 films is repressed from 10−2to10−7A∕cm2 at electric field=3MV∕cm due to the reduction of traps in the HfO2 films. The equivalent oxide thickness also obviously decreased. Besides, the efficiency of terminating traps is relative to the pressure of the SCCO2 fluids.

A low-temperature method, supercritical CO2 fluid (SCF) technology, is proposed to improve the dielectric properties of ultrathin hafnium oxide (HfO2) film at 150°C without significant formation of parasitic oxide at the interface between HfO2 and Si substrate. In this research, the HfO2 films were deposited by dc sputter at room temperature and post-treated by SCF which is mixed with 5vol% propyl alcohol and 5vol% H2O. From high-resolution transmission electron microscopy image, the interfacial oxide of SCF-treated HfO2 film is only 5Å thick. Additionally, the enhancements in the qualities of sputter-deposited HfO2 film after SCF process are exhibited by x-ray photoelectron spectroscopy and capacitance-voltage (C-V) measurement.

This paper explores the application of supercritical carbon dioxide fluids on the field emission enhancement for vertically aligned carbon nanotubes. The typical heating process cannot effectively activate the deionized-water-rinsed carbon nanotube emitters, exhibiting poorer field emission performance, due to residual moisture uptake in the carbon nanotubes. In contrast, the field emission enhancement can be achieved significantly by applying the supercritical carbon dioxide fluids associated with 3 to 9 vol % propyl alcohol. It is found the cosolvent propyl alcohol plays a critical role in the activation efficiency of supercritical carbon dioxide fluids. A physical model is also deduced to clarify the observation.

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