Impact of different dopants on the switching properties of ferroelectric hafniumoxide

Abstract

The wake-up behavior of ferroelectric thin film capacitors based on doped hafnium oxide dielectrics in TiN-based metal-insulator-metal structures is reported. After field cycling a remanent polarization up to 40 C/cm 2 and a high coercive field of about 1MV/cm was observed. Doping of HfO2 by different dopants with a crystal radius ranging from 54pm (Si) to 132pm (Sr) was evaluated. In all cases, an improved polarization-voltage hysteresis after wake-up cycling is visible. For smaller dopant atoms like Si and Al stronger pinching of the polarization hysteresis appeared with increasing dopant concentration and proved to be stable during cycling. ©2014 The Japan Society of Applied Physics

Ferroelectric HfO2-based materials for next-generation ferroelectric memories

“…For each of the above dopants, the o-phase always exists in a transition region between the m-phase and the t/c-phase in the phase-dopant concentration diagram; and within that region, the ferroelectricity can be induced. 44 The ferroelectric properties measured for various dopants are summarized in Fig. 3.…”

“…We also note that besides the nominal dopant concentrations, the real dopant distributions could also significantly influence the ferroelectric properties of the doped HfO 2 thin films, through either modifying the local phase composition (ferroelectric/antiferroelectric) or causing the local defect accumulation pinning the domain wall motions. 44 (ii) Surface energy effect. Surface energy effect often manifests itself by creating unique structures and properties of small-size crystals which can be quite different from those of bulk materials.…”

Physical Mechanisms behind the Field‐Cycling Behavior of HfO2‐Based Ferroelectric Capacitors

“…Since its discovery ferroelectric behavior has been proven for numerous HfO 2 dopants [2] in a binary mixture with ZrO 2 [3] as well as for pure HfO 2 . [4] Even though a PZT-based ferroelectric field effect transistor was already proposed by Moll et al, [5] these devices never reached the market due to their issues with scalability, compatibility with CMOS (complementary metal oxide semiconductor) processing, and the inherent depolarization field leading to retention issues.…”

Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

“…The impacts of dopant type and concentration on the ferroelectric switching properties have been reviewed by Schroeder et al [1]. Furthermore, ferroelectricity can also be achieved in HfO 2 -ZrO 2 solid-solution [2].…”