Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing, People's Republic of China.
Nanotechnology. 2011 Jun 24;22(25):254008. doi: 10.1088/0957-4484/22/25/254008. Epub 2011 May 16.
Resistance switching behavior has been investigated in as-prepared and oxygen-annealed polycrystalline tungsten oxide films using conductive atomic force microscopy. The oxygen-annealed film appeared more insulative than the as-prepared films. The local current distributions demonstrated the lower conductivity at the grain boundaries than at the grains in the oxygen-annealed films. Reversible resistance switching behavior only occurred at the grain surface region of the oxygen-annealed films and the resistance switching process was described by the local valence change of tungsten ions induced by electrochemical migration of protons or oxygen vacancies. This different resistance switching behavior between the grain and grain boundary surface was attributed to the different oxygen vacancy density caused by the post-annealing process. The present results would be especially meaningful for the fabrication of nanoscale resistive nonvolatile memory devices.
使用导电原子力显微镜研究了未经处理和经氧退火的多晶氧化钨薄膜的电阻开关行为。氧退火后的薄膜比未经处理的薄膜具有更高的绝缘性。局部电流分布表明，氧退火后的薄膜中晶界的电导率低于晶粒的电导率。仅在氧退火薄膜的晶粒表面区域发生可逆电阻开关行为，并且电阻开关过程由质子或氧空位电化学迁移诱导的钨离子局部价态变化来描述。这种晶粒和晶界表面之间不同的电阻开关行为归因于后退火过程中不同的氧空位密度。本研究结果对于制备纳米尺度电阻式非易失性存储器件具有重要意义。
