Parametric impedance analysis vs. admittance spectroscopy on ZnO bicrystalline interfaces 

　　Prof. Jong-Sook Lee 

　　School of Materials Science and Engineering,  

　　Chonnam National University, Korea 

　　时间：2017年2月23日（星期四）下午14:00 

　　地点： 4 号楼 14楼第二会议室  

　　联系人：郑嘹赢  研究员 

　　       李国荣　研究员  

欢迎各位老师同学光临! 

　　Parametric impedance analysis vs. admittance spectroscopy on ZnO bicrystalline interfaces   

　　Jong-Sook Lee¹, Joachim Maier² 

　　School of Materials Science and Engineering, Chonnam National University, 61186 Gwangju, Korea 

　　Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany 

　　*E-mail address: jongsook@jnu.ac.kr 

　　Sb additives in commercial varistors, supposed to play the role of the grain boundary pinning by the formation of the secondary phase particles, lead to the presence of head-to-head (C+|C+) polarity inversion boundaries within individual ZnO grains. Therefore, intergranular boundaries in ZnO varistor ceramics are preferentially of C- (O-face) which are suggested to be responsible for the high performance in the varistor function [1-3]. ZnO bicrystals of C-| C- interfaces were prepared by diffusion bonding at high temperature [4] together with platinum plates which serve as ohmic electrodes [2,3]. With the dc resistance subtracted admittance spectroscopy has been successfully applied to the Schottky barrier of a Pr-doped ZnO bicrystalline interface for the deep level identification [Appl. Phys. Lett. 96 202104 (2010)]. Yet the admittance behavior deviates from that of the ideal RC equivalent circuits which may originate from the broadening of the deep levels or the Fermi level pinning by the high trap concentration. Here we demonstrate the application of impedance analysis using the electrical models for the deep trap levels of ZnO bicrystals doped with various transition metals of Co, Mn, Ni, Cu and the activators of Bi or Pr.   

1. Lee JS, Maier J (2005) High barrier effects of (000-1)|(000-1) zinc oxide bicrystals: Implication for varistor ceramics with inversion boundaries, J. Mater. Res. 20:2101-2109.  
2. Park JL, Park C, Kim DY, Jo W, Park CJ, Jeon SY, Lee JS (2009) Polarity engineering in polycrystalline ZnO by inversion boundaries, Appl. Phys. Lett. 94:252108.  
3. Lee JS, Kim Y, Shin EC, Maier J (2010) Positive temperature coefficient resistor behavior in praseodymium-doped ZnO (000-1)|(000-1) boundaries, Appl. Phys. Lett. 96:202104.  
4. Lee JS, Wiederhorn SM (2004) Effects of polarity on grain-boundary migration, J. Am. Ceram. Soc. 87:1319-1323.