Long Time Data Retention and A Mechanism in Ferroelectric-Gate Field Effect Transistors with HfO_2 Buffer Layer

摘要

A mechanism of the long-time data retention in the p-channel MFIS FETs with Pt/SBT/HfO_2/Si gate structures was proposed. The MFIS FETs used in this study exhibited the drain current on/off ratio of approximately 6 x 10~3 even after 30 days had elapsed at room temperature. From the leakage current characteristics of the MFIS diode, the bulk leakage current density lower than 10~(-12) A/cm~2 was presumed for 30-days data retention. On the other hand, we showed that the decrease of on-state drain current in the retention characteristics was explained by the flat-band voltage shift of approximately -0.3V for 30 days toward negative voltage direction. Therefore, it was also found that the trapped charge density as low as 10~(11) cm~(-2) was needed for obtaining the data retention of 30 days.