Crystallization and electrical resistivity of Cu 2O and CuO obtained by thermal oxidation of Cu thin films on SiO 2/Si substrates

L. De Los Santos Valladares, D. Hurtado Salinas, A. Bustamante Dominguez, D. Acosta Najarro, S. I. Khondaker, T. Mitrelias, C. H.W. Barnes, J. Albino Aguiar, Y. Majima

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Abstract

In this work, we study the crystallization and electrical resistivity of the formed oxides in a Cu/SiO 2/Si thin film after thermal oxidation by ex-situ annealing at different temperatures up to 1000 °C. Upon increasing the annealing temperature, from the X ray diffractogram the phase evolution Cu → Cu + Cu 2O → Cu 2O → Cu 2O + CuO → CuO was detected. Pure Cu 2O films are obtained at 200 °C, whereas uniform CuO films without structural surface defects such as terraces, kinks, porosity or cracks are obtained in the temperature range 300-550 °C. In both oxides, crystallization improves with annealing temperature. A resistivity phase diagram, which is obtained from the current-voltage response, is presented here. The resistivity was expected to increase linearly as a function of the annealing temperature due to evolution of oxides. However, anomalous decreases are observed at different temperatures ranges, this may be related to the improvement of the crystallization and crystallite size when the temperature increases.

Original languageEnglish
Pages (from-to)6368-6374
Number of pages7
JournalThin Solid Films
Volume520
Issue number20
DOIs
StatePublished - 1 Aug 2012
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the Academic Vice-Council of the Universidad Nacional Mayor de San Marcos through its Scientific Initiation Program (contract no. PIC — RR 04572-R-10 ). The work in Cambridge was supported by the European Union Program ALBAN (Grant no. E06D101257PE ) and the Cambridge Overseas Trust . The work in Japan was supported by the Japan Society for the Promotion of Science (Grant no. P12030 ), Grants-in-Aid for Scientific Research on Innovative Areas (No. 20108011 , π-Space) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Collaborative Research Project of the Materials and Structures Laboratory (Tokyo Institute of Technology ) and the World Class University Program, Sunchon National University, Korea . The work in Brazil has been supported by a CAPES grant . The authors are indebted to Dr. J. Llandro, from the University of Cambridge and Drs. Y. Azuma and N. Okabayashi from the Tokyo Institute of Technology for their help during different stages of the experiments.

Keywords

  • Annealing
  • Cupric oxide
  • Cuprous oxide
  • Evaporation
  • Thermal oxidation
  • Thin films
  • X-ray diffraction

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