Numerical Analysis of Metal-Ferroelectric-Semiconductor Field-Effect-Transistors (MFS-FETs) Considering Inhomogeneous Ferroelectric Polarization

Tatsuya KAMEI  Eisuke TOKUMITSU  Hiroshi ISHIWARA  

IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.4   pp.577-583
Publication Date: 1998/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Memory Devices Using High-Dielectric-Constant and Ferroelectric Thin Films)
ferroelectric,  MFSFET,  SrBi2Ta2O9,  Si non-volatile memory,  memory,  

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An improved numerical computation model is presented to calculate the metal-ferroelectric-semiconductor field effect transistor (MFSFET) characteristics with a sufficiently large gate area which can be applied for large drain voltages. In the presented model, the polarization of the ferroelectric gate insulator is inhomogeneous and treated as a variable along the channel. We have calculated electrical properties of SrBi2Ta2O9/Si MFSFETs and demonstrate that the conventional model, in which the polarization of the ferroelectric gate insulator (Pd) is treated as a constant, overestimate the drain current when the drain voltage is large. In addition, effects of the ratio of remanent polarization to spontaneous polarization (Pr/Ps ratio) of the ferroelectric film on the transistor characteristics are discussed.