Microstructure and electrical properties of CeO2 ultra-thin films for MFIS FeRAM applications

• Published in: Transactions of Nonferrous Metals Society of China 2007-12, Vol.17 (Special 1), p.s741-s746
• Main Authors: Tang, Ming-Hua, Zhou, Yi-Chun, Zheng, Xue-Jun, Wei, Qiu-Ping, Cheng, Chuan-Pin, Ye, Zhi, Hu, Zeng-Shun
• Format: Article
• Language: English
• ISSN: 1003-6326

A detailed investigation about the dependence of microstructure and electrical properties on annealing temperature was carried out for cerium oxide(CeO2) ultra-thin films (18 nm to 110 nm) on n-type Si(100) substrates by RF magnetron sputtering. Substrate temperature was kept constant at 400 deg C for all samples. The as-deposited films were subsequently annealed in air ambient at 700, 800 and 900 deg C for 1 h respectively. The crystallinity and surface morphology of the CeO2 films were analyzed with X-ray diffractometer(XRD), scanning electron microscope(SEM), atomic force microscope(AFM) and Raman scattering measurement. Electrical properties of the Au/CeO2/Si/Au structure were examined by high frequency capacitance - voltage (C-V) characteristics at 1 MHz and leakage current density - electric field (J - E) characteristics. A Raman peak of the CeO2 thin films was seen at 463 cm-1. From C - V data, these films exhibit dielectric constants ranging from 18 to 23, the hysteresis width (DeltaVFB) ranging from 0.015 V to 0.12 V and the density of trapped charges ranging from 1.45 x10(11) to 3.01 x10(11) cm 2. A leakage current of 4.75x 10-8 -9.0x10-7 A/cm2 at 2 MV/cm was observed. The experimental results show that the CeO2 buffer layers are suitable for non-volatile metalferroelectric-insulator-semiconductor(MFIS) structure field-effect-transistors(FETs) memory applications.