电泳沉积法制备的Zn_(1-x)Cu_xO薄膜的结构及阻变性能

Structure and Resistive Switching Behaviors of Zn_(1-x)Cu_xO Films Derived by Electrophoretic Deposition

采用电泳沉积法在FTO导电玻璃基片上制备Zn_(1-x)Cu_xO薄膜,并对其微观结构、光致发光谱、伏安特性、保持特性和转换电压分布进行探讨。PL谱表明,Cu掺杂在禁带中引入深受主能级,降低氧空位浓度,导致ZnO薄膜的紫外发光、蓝光发光和绿光发光峰强度降低。所得薄膜的晶粒细小、致密、均匀,具有稳定的双极性阻变特性,开关比R_(off)/R_(on)最高达到10~5,其低阻态(LRS)和高阻态(HRS)的阻变机理分别符合欧姆定律和空间电荷限制传导理论。器件经100次循环测试后开关比无明显变化,呈现出较为良好的抗疲劳特性。Cu掺杂对LRS影响不大,但显著改善了HRS的分散性以及转换电压V_(SET)的分散性。当Cu掺杂量x=0.04时,器件表现出良好的综合性能:R_(off)≈10~6Ω,R_(off)/R_(on)≈10~4,V_(SET)介于0.4~3.03 V之间。

Zn1-xCuxO films were fabricated on FTO substrates by electrophoretic deposition. The microstructure, PL spectra, I-V characteristics, retention measurement and switching voltage distri- bution were investigated. PL spectra indicate that Cu doping introduces deep acceptor level in the bandgap and decreases the concentration of oxygen vacancy, which result in the decreasing intensity of ultraviolet, blue and green luminescence. The deposited films are dense and uniform, and exhibit bipolar resistive switching behaviors with a high OFF/ON ratio of 105. The resistive switching behav- iors are govemed by Ohm＇s law in the LRS and space charge limited conduction （SCLC） in the HRS, respectively. Good endurance characteristics can be retained after 100 switching cycles with- out any obvious fluctuation in Roff/Ron ratio. Cu2＋ doping has little influence on low resistance state （LRS）, but decreases the dispersion in high resistance state （HRS） and switching voltage VSET- When Cu doping content x =0.04, the devices show good properties： Roff≈10^6Ω,Roff/Ron≈10^4, and the value of VSET is 0.4 - 3.03 V.