Visible-light enhanced charge storage characteristics of amorphous Ni-doped HfO2 films

Zhang, T.; Zhang, Zhijun; Chan, Cheuk Ho; Li, L. T.; Wei, MingLong; Meng, Xiangshen; Qiu, Xiaoyan

doi:10.1088/1361-6463/aace65

Cited by 1 publication

(1 citation statement)

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“…HfO 2 [20] , Mg 0.6 Zn 0.4 O [21] , BaTiO 3 [22] 等)改变界面势垒, 有效提高了器件性能. 另一方面, 过渡金属氧化物HfO 2 作为一种宽禁带(5-6 eV)绝缘材料, 常用于制备互补型金属-氧化物-半导体场效应晶体管的栅极 [23] .…”

Section: Rram核心单元通常为金属-绝缘体-金属三unclassified

Tri-level resistive switching characteristics and conductive mechanism of HfO2/NiOx/HfO2 stacks

Chen,

Zhang,

Yin

et al. 2023

Acta Phys. Sin.

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With the extensive integration of portable computers and smartphones with "Internet of Things" technology, further miniaturization, high reading/writing speed and big storage capacity are required for the new generation of non-volatile memory devices. Compared with traditional charge memory and magnetoresistive memory, resistive random access memory(RRAM) based on transition metal oxides is one of the promising candidates due to its low power consumption, small footprint, high stack ability, fast switching speed and multi-level storage capacity. Inspired by the excellent resistive switching characteristics of NiO and HfO2, NiOx films were deposited by magnetron sputtering on the Pt<111> layer and the polycrystalline HfO2 film, respectively. Their microstructures, resistive switching characteristics and conductive mechanisms were studied. X-ray diffractometer data shows the <111> preferred orientation for the NiOx film deposited on the Pt<111> layer but the <100> preferred one for the film deposited on the polycrystalline HfO2 layer. X-ray photoelectron depth profile of Ni2p core level reveals that the NiOx film is the mixture of oxygen-deficient NiO and Ni2O3. NiOx(111) films show bipolar resistive switching(RS) characteristics with a clockwise current-voltage(I-V) loop, but its ratio of the high resistance to the low resistance(RH/RL) is only~10, and its endurance is also poor. The NiOx(200)/HfO2 stack exhibits bipolar RS characteristics with a counterclockwise I-V loop. The RH/RL is greater than 104, the endurance is about 104 cycles, and the retention time exceeds 104 s. In the initial stage, the HfO2/NiOx(200)/HfO2 stack shows similar bi-level RS characteristics with that of the NiOx(200)/HfO2 stack. However, in the middle and the last stages, it's I-V curves gradually evolve into tri-level RS characteristics with a "two-step Set process" in the positive voltage region, showing potential applications in multilevel nonvolatile memory devices and brain-like neural synapses. Its I-V curves in the high and the low resistance states follow the relationship of Ohmic conduction (I∝V), while the I-V curves in the intermediate resistance state are dominated by the space-charge-limited-current mechanism (I∝V2). The tri-level RS phenomena are attributed to the coexistence of the oxygen-vacancy conductive filaments in the NiOx(200) film and the space charge limited current in the upper HfO2 film.

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