Write-Once-Read-Many-Times Nonvolatile Memory Characteristics of Sol–Gel Hafnium Zirconium Oxide

In this article, write-once-read-many-times (WORM) memory behavior of HfZrO (HZO) ferroelectric material is demonstrated. A stoichiometric Hf0.5Zr0.5O2 thin film prepared using a sol–gel process is used as a resistive switching (RS) layer. The top and bottom electrodes are Al and n+-Si, respectively. The Al/HZO/n+-Si memory shows a low current of
$10^{-{11}}$
A at a read voltage of 0.6 V in the OFF state. A writing process occurs when the voltage on Al electrode increases to ~2.8 V. The ratio of the OFF-state resistance (
${R}_{\text {off}}{)}$
to ON-state resistance (
${R}_{\text {on}}{)}$
is
$10^{{6}}$
. Both data retention and stress tests indicate that
${R}_{\text {off}}$
and
${R}_{\text {on}}$
can remain the same for over
$10^{{4}}$
s. Moreover, data stability is further confirmed at an elevated temperature of 85 °C. The switching speed of the HZO memory is ~40 ns, corresponding to a power consumption of 0.98 nJ. The RS mechanism is investigated, and the carrier conduction mechanisms are studied by the analysis of current–voltage characteristics at different temperatures.