AIP Advances (Oct 2022)

p-type conversion of distorted SnOx thin film by mild thermal annealing treatment in pure N2 environment

  • Kotaro Watanabe,
  • Takuma Kawaguchi,
  • Shinya Aikawa

DOI
https://doi.org/10.1063/5.0103337
Journal volume & issue
Vol. 12, no. 10
pp. 105102 – 105102-7

Abstract

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Tin oxide semiconductors can achieve both n- and p-type conduction, depending on the oxidation state of Sn. An n-type conduction can easily be fabricated; however, considerable optimization is required for fabrication of a p-type behavior. In this study, n-type SnOx thin films, prepared by reactive magnetron sputtering, were converted to p-type behavior using only post-deposition annealing at 600 °C in a pure nitrogen atmosphere. The annealing-temperature-dependent electrical properties of the SnOx thin films led to a remarkable increase in the yield of p-type behavior at 600 °C. X-ray diffraction analysis revealed that the SnOx film had a SnO2-dominant crystal phase and also suggested that N2 molecules dissociated at 600 °C and filled the oxygen vacancy (VO) site as atomic nitrogen. A detailed analysis of the binding state by x-ray photoelectron spectroscopy confirmed an increase in SnO-derived components, the appearance of peaks derived from N–Sn bonding, a decrease in VO caused by nitrogen doping, and charge transfer. Thus, we found that addition of nitrogen atoms promotes a chemical shift from Sn4+ to Sn2+ and that simultaneously passivates VO and contributes to hole generation.