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HfO2 and (Bi,La)4Ti3O12 were chosen as the respective buffer layer and ferroelectric flm in forming MFIS (metal-ferroelectric-insulator-semiconductor) diodes on Si(100) substrates. HfO2 flms were prepared by an MBD (molecular beam deposition) method, and they were subjected to ex-situ O2 annealing in a rapid thermal annealing (RTA) furnace at 800 C for 1 min. In order to obtain optimal properties, especially the electrical leakage current characteristic, three kinds of HfO2 flms were prepared, which were deposited at room temperature, at 300 C substrate temperature,and with chemical oxidation. On the HfO2/Si structures, Bi3:45La0:75Ti3O12 flms ranging from 300 nm to 400 nm in thickness were deposited by a sol-gel technique and they were crystallized in O2 atmosphere at 750 C . The memory window width in the C-V (capacitance-voltage) curve of the BLT/HfO2/Si diode was about 1.0 V for a voltage sweep of  6 V. It was also found that the retention time of this diode was longer than 8 hours.