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. Th en, 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 w ere amorphous even after the annealing process. No hysteretic characteristi cs were observed in the capacitance-voltage (C-V) measurement and the diele ctric constant of the LaAlO3 films was estimated to be 21-25. It was also f ound that the leakage current density decreased by about three orders of ma gnitude after the annealing process. On these films, Sr0.8Bi2.2Ta2O9 films with 210 nm thickness were deposited by a sol-gel method. All samples annea led in O-2 atmosphere at temperatures ranging from 650 to 750 degreesC show ed hysteretic C-V characteristics, and the memory window width in the sampl e annealed at 750 degreesC for 30 min was about 3.0 V for a voltage sweep o f +/- 10 V. It was also found that the capacitance values biased in the hys teresis loop were unchanged over 12 h. (C) 2001 American Institute of Physi cs.