High polarization, endurance and retention in sub-5 nm Hf_0.5Zr_0.5O₂ films

Abstract

Ferroelectric HfO 2 is a promising material for new memory devices, but significant improvement of its important properties is necessary for practical application. However, previous literature shows that a dilemma exists between polarization, endurance and retention. Since all these properties should be simultaneously high, overcoming this issue is of the highest relevance. Here, we demonstrate that high crystalline quality sub-5 nm Hf 0.5 Zr 0.5 O 2 capacitors, integrated epitaxially with Si(001), present combined high polarization (2P r of 27 µC cm −2 in the pristine state), endurance (2P r > 6 µC cm −2 after 10 11 cycles) and retention (2P r > 12 µC cm −2 extrapolated at 10 years) using the same poling conditions (2.5 V). This achievement is demonstrated in films thinner than 5 nm, thus opening bright possibilities in ferroelectric tunnel junctions and other devices.This journal is

Epitaxial Ferroelectric HfO2 Films: Growth, Properties, and Devices

“…In polycrystalline doped-HfO2 films, the relative amount of paraelectric monoclinic phase respect the ferroelectric orthorhombic phase is found to increase with film thickness. [14][15][16] This dependence, which can influence critically the ferroelectric properties, has been observed too in epitaxial YHO 80 and HZO films 53,85 films.…”

Epitaxial Ferroelectric La-Doped Hf0.5Zr0.5O2 Thin Films

“…15,22 Endurance of epitaxial HZO films can be high in spite of their enormous E c of 3-4 MV/cm. 10,14,16,22 Indeed, endurance of 10 11 cycles has been measured in sub-5 nm HZO films applying a very large electric field above 5 MV/cm. 22 Further improvement could be achieved by decreasing leakage and the huge E c of epitaxial films.…”

Extraction of Preisach Model Parameters for Fluorite-Structure Ferroelectrics and Antiferroelectrics

“…The proposed modeling framework was used to extract ferroelectric parameters for Al-doped 6,7 , Gd-doped 8 , La-doped 9 , Si-doped 1,[10][11][12] , Sr-doped 13 , Y-doped 14,15 , Zr-doped 4,10,[16][17][18][19][20][21][22][23][24][25][26] , and undoped 4,5 HfO 2 thin films reported in the literature as shown in Fig. 6.…”

“…Ferroelectric field-effect transistors (FeFETs), as emerging memory, find a niche in such applications due to their ultra-fast program/erase time, low operation voltage, and low power consumption [1][2][3] . Despite the fact that hafnium oxide 4,5 and its doped variants (Al-doped 6,7 , Gd-doped 8 , La-doped 9 , Si-doped 1,[10][11][12] , Sr-doped 13 , Y-doped 14,15 , Zr-doped 4,10,[16][17][18][19][20][21][22][23][24][25][26] ) have been extensively studied and characterized over the past few years, little has been done to aggregate those data into ferroelectric properties to provide the insight necessary to create a predictive model for ferroelectrics. Such a predictive model cannot be realized without the accurate determination of a multitude of ferroelectric parameters from various experimental hysteresis loops (Q FE -E FE ).…”