ZnO压敏电阻界面导电特性研究

Study on interfacial electrical properties of ZnO varistor

采用相同的工艺制备ZnO压敏电阻和未掺杂ZnO陶瓷片后,用扫描电镜(SEM)、电阻率计和X射线光电子能谱(XPS)对它们形貌、电阻率、界面化学计量比和电子状态进行了研究。实验发现:未掺杂ZnO晶粒粒径小于10μm且均匀性差;ZnO电阻率对烧结气氛敏感,其值在2.36～47.97Ω·cm之间,界面存在非化学计量氧锌比,O/Zn=1.29。掺杂后,ZnO压敏电阻界面价电子峰减小,证实压敏电阻陷阱态的存在,表明需用载流子陷阱态补充双肖特基势垒模型。

By the same process, ZnO varistor and undoped ZnO ceramic were prepared and investigated using SEM, ohmmeter and X-ray photoelectron spectroscopy (XPS). The results show that the average grain size of undoped polycrystalline ZnO was less than 10 μm with uneven distribution; its resistivity, which is sensitive to sintering atmosphere, varies from 2.36 to 47.97 Ω&middotcm and the non-stoichiometric ratio of O/Zn was 1.29 at the interface. Due to the peak of ZnO varistor interface vanishes in XPS valence spectrum, it suggests that some states of trap exist in the interface of ZnO varistor and these states should be taken into consideration in Double Schottky Barrier (DSB) model.