Role of grain boundaries in ZnO

Yukio Sato, Yuichi Ikuhara

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

ZnO is used in a wide variety of applications owing to the electrical properties. Polycrystalline ZnO ceramics have long been used such as varistor, and ZnO films are currently intensively studied for transparent conductor applications. Grain boundary (GB) in ZnO varistor is believed to be the origin of nonlinear current-voltage characteristics, and GB in ZnO films possibly affects the electrical conductivity. It is therefore important to understand the role of ZnO GB on the electrical properties, which should be closely related with the structure in atomic scale. With these viewpoints, we have studied the atomistic structure of ZnO GBs, where the orientation relations of adjacent crystals are well defined. Single GBs studied were obtained by fabricating ZnO bicrystals and the GBs were characterized by scanning transmission electron microscopy (STEM) and theoretical calculations. It is found that coordination number of ions change in ZnO GBs; there are underfold or overfold coordinated ions that are unusual in bulk inside. It is calculated that these atomistic structures alters the electronic structure but would not create deep states in the band gap. On the other hand, when praseodymium (Pr), which is known to be a key dopant element to obtain nonlinear (I-V) characteristics, is added to the GBs, Pr strongly localizes to the GBs and occupies specific atomic sites. Pr facilitates the formation of the acceptorlike defects such as zinc vacancies, which we think that is an important role of Pr on generation of nonlinear (I-V) characteristics. Furthermore, atomic arrangement and localization behavior of Pr are studied for several GBs to obtain fundamental understanding about GB structure formation.

Original languageEnglish
Title of host publicationOxide-Based Materials and Devices V
PublisherSPIE
Volume8987
ISBN (Print)9780819499004
DOIs
Publication statusPublished - 2014
Externally publishedYes
Event5th Annual Oxide Based Materials and Devices Conference - San Francisco, CA, United States
Duration: Feb 2 2014Feb 5 2014

Other

Other5th Annual Oxide Based Materials and Devices Conference
CountryUnited States
CitySan Francisco, CA
Period2/2/142/5/14

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All Science Journal Classification (ASJC) codes

  • Applied Mathematics
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Sato, Y., & Ikuhara, Y. (2014). Role of grain boundaries in ZnO. In Oxide-Based Materials and Devices V (Vol. 8987). [89871B] SPIE. https://doi.org/10.1117/12.2042752