Polarization and resistive switching in epitaxial 2 nm Hf$_{0.5}$Zr$_{0.5}$O$_2$ tunnel junctions

Milena Cervo Sulzbach; Huan Tan; Saul Estandia; Jaume Gazquez; Florencio Sanchez; Ignasi Fina; Josep Fontcuberta

doi:10.1021/acsaelm.1c00604

paper

Polarization and resistive switching in epitaxial 2 nm Hf $_{0.5}$ Zr $_{0.5}$ O $_{2}$ tunnel junctions

arXiv:2108.10373 · doi:10.1021/acsaelm.1c00604

Abstract

In the quest for reliable and power-efficient memristive devices, ferroelectric tunnel junctions are being investigated as potential candidates. CMOS-compatible ferroelectric hafnium oxides are at the forefront. However, in epitaxial tunnel devices with thicknesses around $\approx$ 4 - 6 nm, the relatively high tunnel energy barrier produces a large resistance that challenges their implementation. Here, we show that ferroelectric and electroresistive switching can be observed in ultrathin 2 nm epitaxial Hf $_{0.5}$ Zr $_{0.5}$ O $_{2}$ (HZO) tunnel junctions in large area capacitors ( $\approx 300 μ m^{2}$ ). We observe that the resistance area product is reduced to about 160 $Ω \cdot$ cm $^{2}$ and 65 $Ω \cdot$ cm $^{2}$ for OFF and ON resistance states, respectively. These values are two orders of magnitude smaller than those obtained in equivalent 5 nm HZO tunnel devices while preserving a similar OFF/ON resistance ratio (210 $%$ ). The devices show memristive and spike-timing-dependent plasticity (STDP) behavior and good retention. Electroresistance and ferroelectric loops closely coincide, signaling ferroelectric switching as a driving mechanism for resistance change.

References in corpus (11)

Cited by in corpus (1)

Ultrahigh oxygen ion mobility in ferroelectric hafnia

Polarization and resistive switching in epitaxial 2 nm Hf0.5​Zr0.5​O2​ tunnel junctions

Abstract

References in corpus (11)

Cited by in corpus (1)

Polarization and resistive switching in epitaxial 2 nm Hf $_{0.5}$ Zr $_{0.5}$ O $_{2}$ tunnel junctions