Current status of ferroelectric-gate Si transistors and challenge to ferroelectric-gate CNT transistors

Current status of ferroelectric-gate FETs (field effect transistors) is reviewed. First, characteristics of Si FETs with MRS (metal-ferroelectric-insulator-semiconductor) gate structures are discussed. It has been shown that the data retention characteristics of ferroelectric-gate FETs are much improved by use of HfO(2)-based buffer layers which are inserted between the ferroelectric-gate film and Si substrate for preventing inter-diffusion of constituent elements. Then, usefulness of organic ferroelectrics such as copolymers of vinyliden fluoride and trifluoroethylene (P(VDF-TrFE)) in fabrication of MRS devices is demonstrated. In an Au/P(VDF-TrFE)/Ta(2)O(5)/Si MFIS diode, a memory window as wide as 2.9 V has been obtained with a voltage sweep of 4 V. Finally, operation mechanisms in ferroelectric-gate CNT (carbon nano-tube) transistors are discussed, assuming Schottky barrier conduction at the source and drain contacts. (C) 2008 Elsevier B.V. All rights reserved.