Control of polarity of heteroepitaxial ZnO films by interface engineering

Soon Ku Hong, Takashi Hanada, Yefen Chen, Hang Ju Ko, Takafumi Yao, Daisuke Imai, Kiyoaki Araki, Makoto Shinohara

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Control of polarity of heteroepitaxial ZnO films has been examined by interface engineering. ZnO films were grown by plasma-assisted molecular beam epitaxy on Ga-polar GaN template and c-plane sapphire substrates. Polarity of all the samples is determined by coaxial impact collision ion scattering spectroscopy. Zn- and O-polar ZnO films have successfully grown by Zn- and O-plasma pre-exposures on Ga-polar GaN templates prior to ZnO growth. High-resolution transmission electron microscopy revealed formation of a single-crystalline monoclinic Ga2O3 interface layer by O-plasma pre-exposure on Ga-polar GaN templates, while no interface layer was observed for Zn pre-exposed ZnO films. The polarity of ZnO films grown under oxygen ambient on c-plane sapphire with MgO buffer is revealed as O-polar. Fabrication of polarity inverted ZnO heterostructure has been studied: polarity of ZnO films on Ga-polar GaN templates was changed from Zn-polar to O-polar by inserting a MgO layer. High-resolution transmission electron microscopy revealed atomically flat interfaces at both lower and upper ZnO/MgO interfaces and no inversion domain boundaries were detected in the upper ZnO layer.

Original languageEnglish
Pages (from-to)491-497
Number of pages7
JournalApplied Surface Science
Volume190
Issue number1-4
DOIs
Publication statusPublished - 2002 May 8

Keywords

  • GaN
  • Interface
  • Interface engineering
  • Polarity
  • Polarity inversion
  • ZnO

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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