Resistive switching properties of plasma enhanced-ALD La2O3 for novel nonvolatile memory application

Abstract

Plasma enhanced (PE) atomic layer deposition (ALD) of lanthanum oxide films on silicon and platinum substrates were examined using lanthanum-2,2,6,6-tetramethyl-3,5-heptanedione, and O2 plasma as precursors. The effect of pulse time and deposition temperature on the growth rate was investigated. Resistive switching behaviors of La2O3 prepared by PE-ALD were investigated as a promising candidate for next generation nonvolatile memory technology. The crystalline structure of the obtained film was found to be polycrystalline by transmission electron microscope and the chemical composition of the film was estimated to be stoichiometric La2O3 by x ray photoelectron spectroscopy. The low resistance ON state and high resistance OFF state can be reversibly altered under a low voltage about 1.5 and −0.6 V. More than 1000 reproducible switching cycles by dc voltage sweep were observed with a resistance ratio above 100, which was large enough to read out without obvious degradation. Moreover, the estimated working characteristics such as set and reset voltages distribution were sufficiently stable to fulfill requirement for memory application. Considering the excellent memory switching behavior, resistance switch device composed of a promising ALD high-k La2O3 dielectric film is a possible candidate to be integrated into future memory processes.