A Theoretical Study of Negative Capacitance Field‐Effect Transistors Using Ferroelectrics Having First‐ and Second‐Order Phase Transitions

Abstract

Herein, a theoretical study of negative capacitance field‐effect transistors (NCFETs) using ferroelectrics (FEs), having first‐ and second‐order phase transitions (FPT and SPT, respectively), applying the Landau–Devonshire (LD) theory, is presented. The expressions for the Landau parameters for FPT FEs are derived from the basic relations, and subsequently, these are used in the numerical models for the surface potential, gate charge, and drain current for NCFETs with FPT FEs, developed in this work. The results show an excellent match with those obtained from technology computer‐aided design (TCAD) simulations. Next, the Landau parameters and the numerical models for the charge and drain current for NCFETs with SPT FEs are developed, following a similar procedure, and then the results of these two structures are compared, along with those obtained from TCAD simulations, which shows an excellent match. The results bring out some interesting observations—notable among them is a higher Ion/Ioff ratio for FPT structures, as compared to that for SPT ones, caused by a reduction in the subthreshold current, with a marginal increase in the strong inversion current in the former. This feature, by itself, may make NCFETs with FPT FEs more suitable than those with SPT FEs for low‐power applications.