A low temperature preparation of Sr_0.7Bi_2+x.Ta₂O₉ thin films on SiO₂/Si by pulsed laser deposition for application of metal-ferroelectric-insulator-semiconductor structure

Abstract

Preferentially (105)-oriented Sr_0.7B1_2.8Ta₂O₉ thin films on SiO₂/n-Si(100) have been prepared by Pulsed Laser Deposition (PLD) at low temperature as low as 350°C, which is the lowest process temperature for growing Sr _x Bi_yTa₂O₉(SBTO) ferroelectric thin films. Insulating properties of the SBTO film have been improved by lowering the process temperature or by increasing Sr/Bi atomic ratio from 0.7/2.8 to 0.7/2.0. After applying the low leakage SBTO films to Metal-Ferroelectric-Insulator-Semiconductor diode structures, it is finally observed that their C-V curves have counterclockwise dielectric hysteresis that indicates the films' ferroelectric hysteresis sufficiently control the Si surface potential. A low temperature process in preparing ferroelectric thin film and Sr-deficient and Bi-excess SBTO thin film by PLD method are very effective and promising for realizing an excellent MFIS FET structure.

Key Words:

• ferroelectric thin film
• Sr_xBi_yTa₂O₉ (SBTO)
• Pulsed Laser Deposition (PLD)
• Metal-Ferroelectric-lnsulator-Semiconductor (MFIS)