Electrical Characteristics of the Pt/SBT/TiO 2 /Si MFIS Structures with Thickness Variation of the SBT Film
- PDF / 199,028 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 18 Downloads / 201 Views
Electrical Characteristics of the Pt/SBT/TiO2/Si MFIS Structures with Thickness Variation of the SBT Film
Ji-Woong Kim, Kwang-Yong Lee, Jae-Hoon Choi, and Tae-Sung Oh Department of Metallurgical Engineering and Materials Science, Hong Ik University, Seoul 121-791, Korea
ABSTRACT
Pt/Sr0.85Bi2.4Ta2O9/TiO2/Si structures were prepared with variation of the Sr0.85Bi2.4Ta2O9 (SBT) film thickness for MFIS-FET applications. After depositing TiO2 film of 10 nm thickness by reactive sputtering on Si(100) substrate as a buffer layer, SBT thin film of 210-400 nm thickness was prepared onto it by metal organic decomposition process. Regardless of the SBT film thickness, the Pt/SBT/TiO2/Si structures exhibited clockwise directional hysteresis, indicating well-defined ferroelectric switching behavior of the SBT films. While the memory window of the Pt/SBT/TiO2/Si MFIS structures increased with increasing the SBT film thickness, the maximum capacitance of the Pt/SBT/TiO2/Si MFIS structures decreased with increasing the SBT film thickness. The Pt/SBT(400 nm)/TiO2(10 nm)/Si structure exhibited a memory window of 1.3 V at ±5 V. INTRODUCTION
Ferroelectric thin films have been extensively studied for use in nonvolatile memory applications due to their attractive electrical properties such as remanent polarization and switchable characteristics[1-3]. Thin films of PbTiO3 and PbZrxTi1-xO3 have been widely investigated as ferroelectric materials for nonvolatile memory, because of their high polarization values and low annealing temperatures. However, these materials have the serious problem that the remanent polarization decreases after repetitive polarization switching, i.e., the polarization fatigue[4]. Recently, researches have been focused on the SrBi2Ta2O9 thin films of bismuth layered perovskite structure due to their fatigue-free ferroelectric characteristics[1-3]. Among the nonvolatile ferroelectric memories, metal-ferroelectric-semiconductor field effect transistor (MFS-FET), in which the ferroelectric thin film is used as a gate material, has potential for non-destructive readout and high integration density. However, it is difficult to obtain a good interface between ferroelectrics and Si due to the interfacial reaction and charge injection. In order to overcome such problems of MFS structure, it is proposed that an oxide layer such as CeO2, Y2O3, and SrTiO3 is used as a buffer layer between ferroelectrics and Si[4]. In this study, we have prepared the Pt/Sr0.85Bi2Ta2O9(210-400 nm)/TiO2(10 nm)/Si structure using TiO2 as a buffer layer between Sr0.85Bi2Ta2O9 (SBT) ferroelectric thin film and Si substrate, and then investigated the electrical properties of the Pt/SBT/TiO2/Si structure with variation of the SBT film thickness.
F3.1.1
EXPERIMENTAL DETAILS
To fabricate the Pt/SBT/TiO2/Si structure, TiO2 buffer layer of 10 nm thickness was deposited on RCA-cleaned p-type Si(100) substrate using DC reactive sputtering at room temperature. Thickness of the TiO2 film was measured by ellipsometry. SBT thin films were prepared on t
Data Loading...
