Detecting minute amounts of nitrogen in GaNAs thin films using STEM and CBED

Maryam Vatanparast, Yu Tsun Shao, Mohana Rajpalke, Bjørn Ove Fimland, Turid Reenaas, Randi Holmestad, Per Erik Vullum, Jian Min Zuo

Research output: Contribution to journalArticlepeer-review

Abstract

Nitrogen (N) is a common element added to GaAs for band gap engineering and strain compensation. However, detection of small amounts of N is difficult for electron microscopy as well as for other chemical analysis techniques. In this work, N in GaAs is examined by using different transmission electron microscopy (TEM) techniques. While both dark-field TEM imaging using the composition sensitive (002) reflections and selected area diffraction reveal a significant difference between the doped thin-film and the GaAs substrate, spectroscopy techniques such as electron energy loss and energy dispersive X-ray spectroscopy are not able to detect N. To quantify the N content, quantitative convergent beam electron diffraction (QCBED) is used, which gives a direct evidence of N substitution and As vacancies. The measurements are enabled by the electron energy-filtered scanning CBED technique. These results demonstrate a sensitive method for composition analysis based on quantitative electron diffraction.

Original languageEnglish (US)
Article number113299
JournalUltramicroscopy
DOIs
StateAccepted/In press - 2021

Keywords

  • Convergent beam electron diffraction (CBED)
  • Gallium arsenide (GaAs)
  • Scanning transmission electron microscopy (STEM)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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