Defect states and charge trapping characteristics of HfO_2 films for high performance nonvolatile memory applications

摘要

In this work, we present significant charge trapping memory effects of the metal-hafnium oxide-SiO_2-Si (MHOS) structure. The devices based on 800℃ annealed HfO_2 film exhibit a large memory window of ～5.1 V under ±10 V sweeping voltages and excellent charge retention properties with only small charge loss of ～2.6% after more than 10~4s retention. The outstanding memory characteristics are attributed to the high density of deep defect states in HfO_2 films. We investigated the defect states in the HfO_2 films by photoluminescence and photoluminescence excitation measurements and found that the defect states distributed in deep energy levels ranging from 1.1 eV to 2.9 eV below the conduction band. Our work provides further insights for the charge trapping mechanisms of the HfO_2 based MHOS devices.