High mobility hydrogenated zinc oxide thin films

Diana Gaspar, L. Pereira, K. Gehrke, B. Galler, E. Fortunato, R. Martins

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)

Abstract

In this work we present a comprehensive study of the role of hydrogen in the structure, morphology, composition and electro-optical properties of zinc oxide thin films deposited by rf reactive magnetron sputtering at room temperature. The transparency and conductivity of the in situ hydrogenated zinc oxide films (ZnO:H) are improved with the addition of H2 to the sputtering atmosphere, where the resistivity dropped one order of magnitude (from 3×10−2 to 2.8×10−3 Ωcm) for an optimal dilution of 1.5% in argon. The effect of hydrogen in the conductivity of undoped ZnO thin films has been attributed to the shallow donor behaviour. However, we observed that the increase in the conductivity came essentially from the improvement of the mobility that reached 47.1 cm2/Vs for a carrier concentration of 4.4×1019 cm−3. This improvement in the mobility happens with an effective hydrogen incorporation into the bulk of the sputtered ZnO:H films, being attributed to the passivation of grain boundaries trap states while carrier concentration is dominated by the formation of Zn interstitials.

Original languageEnglish
Pages (from-to)255-262
Number of pages8
JournalSolar Energy Materials and Solar Cells
Volume163
DOIs
Publication statusPublished - 1 Apr 2017

Keywords

  • Hydrogen doping
  • Rf sputtering
  • Transparent conducting oxide
  • Zinc oxide

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