Spatially resolved steady-state negative capacitance

Modeling of Negative Capacitance in Ferroelectric Thin Films

“…The modification of the domain wall period only for the t F = 10 nm case was necessary because the compact model inherently assumes the abrupt domain wall structure (Kittel approximation), whereas there must be a small amount of the smooth change in the polarization at DW. When the film thickness is thick enough (>25 nm) this effect could be neglected, but for the thinner case, this effect cannot be ignored . C–T formalism shows that a soft domain structure with a gradual domain wall evolves in the ultrathin film .…”

“…C–T formalism shows that a soft domain structure with a gradual domain wall evolves in the ultrathin film . In this regime, the compact model based on the hard domain structure is no longer accurate, and a single‐harmonic approximation model can be effectively applied to investigate the electronic properties of the soft domains and the NC effect from the structure . A detailed analysis and discussion on the aspect are addressed in Section S7 (Supporting Information).…”

Stepwise internal potential jumps caused by multiple-domain polarization flips in metal/ferroelectric/metal/paraelectric/metal stack

“…In a decade, many groups have focused on studying NC effects in FE/PE stacks and FE/PE gate stack FETs . Concerning NC effects in FE/PE stacks, three kinds of demonstrations have been provided experimentally so far: (i) total capacitance enhancement in the case of no internal metal between FE and PE layers [2][3][4] , (ii) transient NC effects in AC mode operation [5][6][7] , and (iii) locally stabilized NC state 8 . Several models of quasi-static NC associated with domain wall motion in a multiple-domain system have been also proposed [9][10][11][12][13] .…”

Subthreshold Characteristics of a Metal-Oxide–Semiconductor Field-Effect Transistor with External PVDF Gate Capacitance

“…At least two different approaches have been proposed: (1) to use the tunnel junction at the source/channel end of the MOSFET (called the tunnel field-effect transistor or tunnel FET) [11][12][13][14]; and (2) to use the negative gate capacitance of the MOSFET. Negative capacitance has been observed in many different materials and device structures including ferroelastic switches, oxidesuperlattices, supercrystals, and light-emitting diodes [15][16][17][18][19][20][21]. It can be practically achieved by utilizing ferroelectric dielectric materials such as AlInN [8], BiFeO 3 [9], and HfZrO 2 [14], due to the lag of the polarization charge inside the ferroelectric materials with respect to the change of applied voltage.…”