Effect of thickness-dependent crystal mosaicity and chemical defect on electric properties in yttrium-stabilized epitaxial HfO_2 thin films

摘要

Epitaxial pseudo cubic yttrium-stabilized Y_(0.05)Hf_(0.95)O_2 (YHO) thin films with bottom electrode layers of Pr_(0.5)Sr_(0.5)CoO_3 were deposited on (001)-oriented LaA1O_3 (LAO) substrates by using the pulsed laser deposition system. The crystal structure and thickness of the films were confirmed by 6-26 scan and X-ray reflectivity via X-ray diffraction technology, respectively. Reciprocal space mapping (RSM) was performed to clarify the microstructure of the epitaxial YHO films affected by LAO substrates, and the result of symmetric RSMs revealed that the crystal mosaicity of the YHO films increases with the increasing film thicknesses. Moreover, the dominant conduction mechanisms of all the YHO films were ohmic conduction in the low electric field. At a high applied electric field, the YHO-5.4nm film was determined by the space-charge-limited current behavior, while the samples of the YHO-9.8nm and YHO-19.2nm films were determined by ohmic conduc-tion. The temperature-dependent I-V characteristics of the YHO films with different thicknesses have been also obtained, revealing that the current of all the YHO films generally increases with the increase in temperature, which attributed to the crystal mosaicity and chemical defects.