Fabrication and electrical properties of ferroelectric-gate FETS with epitaxial gate structures

We have fabricated ferroelectric-gate FETs with an epitaxially grown insulator-ferroelectric gate structure. Our prior success in growing epitaxial layers of SrBi2Ta2O9 with the c-axis oriented at a 45degrees angle to the normal of the substrate plane enabled us to grow diode structures whose C-V characteristics exhibited memory effects arising from the ferroelectric's remanent polarization. We confirmed that data encoded as capacitance changes arising from the layer's ferroelectricity could be preserved for periods of over 10 days. We then grew FET structures, and examined their I-d-V-g characteristics. Our examination revealed a five-order-of-magnitude value for the on/off drain current ratio, as well as memory characteristics. We confirmed that data encoded as drain current changes based on ferroelectricity could be stored for over 2 hours. (C) 2003 Wiley Periodicals, Inc.