Key Laboratory of Inorganic Functional Material and Device, CAS Shanghai Institute of Ceramics, Chinese Academy of Sciences 

中国科学院无机功能材料与器件重点实验室 

SEMINAR

ROLE OF INTERFACES IN FERROELECTRIC

MEMORY CELLS 

Speaker: A. S. Sigov 

MIREA – Russian Technological University, 78 Vernadsky Avenue, 119454 Moscow, Russia 

报告时间：2019年10月16日（星期三）14: 30 

报告地点：G3第1会议室 

联系人：李国荣 研究员  武安华 研究员 

欢迎广大科研人员和研究生参加！ 

　　报告简介： 

　　Integrated ferroelectric devices now are a growing part of semiconductor industry, for example Ferroelectric Random Access Memory (FRAM) and piezoelectric MEMS. FRAM is a nonvolatile memory with good speed and endurance, however commercial devices demonstrate a fairly low integration degree. One of the reasons of poor scaling of FRAM is a rapid degradation of ferroelectric properties with the film thickness decreasing.  

　　This challenge is usually discussed in the framework of the dead layer model – a passive nonferroelectric layer at the metal-ferroelectric interface. It is commonly supposed, that the dead layer is a reason of properties degradation with the ferroelectric film thickness decrease, including decreasing polarization, hysteresis slope, dielectric permittivity, fatigue and other parameters. 

　　In this work we discuss different models for estimation of the dead layer thickness at the ferroelectric film-metal interface, including the small-signal capacitance model and two methods based on dielectric hysteresis analysis—one based on slopes of the hysteresis loops at the coercive field and the new one based on comparison of dielectric hysteresis portraits. It is shown that the latter technique yields more reliable data as it excludes the effect of leakage and relaxation loss. Conductivity may have a pronounced effect on the validity of dead-layer thickness data. We report data for the dead layer thickness of the PZT films with different crystalline structure.