Electrical properties of LaAlO3/Si and Sr0.8Bi2.2Ta2O9/LaAlO3/Si structures

Lanthanum aluminate (LaAlO3) films were deposited on Si(100) substrates by evaporating single-crystal pellets in vacuum using an electron-beam gun. Then, they were annealed in N-2 ambience at 700 degreesC for 10 min using an electric furnace. X-ray diffraction analysis showed that the LaAlO3 films were amorphous even after the annealing process. No hysteretic characteristics were observed in the capacitance-voltage (C-V) measurement and the dielectric constant of the LaAlO3 films was estimated to be 21-25. It was also found that the leakage current density decreased by about three orders of magnitude after the annealing process. On these films, Sr0.8Bi2.2Ta2O9 films with 210 nm thickness were deposited by a sol-gel method. All samples annealed in O-2 atmosphere at temperatures ranging from 650 to 750 degreesC showed hysteretic C-V characteristics, and the memory window width in the sample annealed at 750 degreesC for 30 min was about 3.0 V for a voltage sweep of +/- 10 V. It was also found that the capacitance values biased in the hysteresis loop were unchanged over 12 h. (C) 2001 American Institute of Physics.