FORMATION OF FERROELECTRIC (Bi, Nd)_4Ti_3O_(12) THIN FILMS ON HfO_2/Si(100) STRUCTURES FOR MFIS-TYPE FERROELECTRIC MEMORY APPLICATIONS

摘要

MFIS (metal-ferroelectric-insulator-semiconductor) diodes and transistors having a BNT((Bi, Nd)_4Ti_3O_(12))/HfO_2/Si (100) structure were fabricated and their data retention characteristics were characterized. HfO_2 and BNT thin films were formed by E-B (electron beam) deposition and chemical solution deposition (CSD) methods, respectively. The Pt/BNT/HfO_2/Si MFIS diodes showed the hysteretic-V (capacitance-voltage) characteristic and the retention time was as long as 5 days. In the case of the Pt/BNT/HfO_2/Si MFIS transistor, the drain current on-off ratio was larger than 10~4 initially and it was about 1,000 at a time of 1 day after the "write" operation.