Evaluation of zinc interstitial in Si-ion implanted ZnO bulk single crystals by a Rutherford backscattering study: An origin of low resistivity

Abstract

The relation between low resistivity and Zn interstitial in ZnO single crystals implanted with the peak Si atomic concentration of 2.62 × 1020 cm−3 is studied by combining Rutherford backscattering spectroscopy/channeling, photoluminescence, and Van der Pauw methods. The variation in resistivity from ∼104 Ω cm for un-implanted ZnO to ∼10−3 Ω cm for as-implanted ones is observed. The lattice displacement of Zn atoms of ∼0.10 Å from the 〈0 0 0 1〉 row is estimated from the normalized angular yield profiles, preserving the single crystallinity in as-implanted ZnO with a minimum yield (χmin) of ∼11%. The low resistance is maintained by the 1000 °C annealing, accompanied with the lattice displacement of Zn atoms of ∼0.07 Å. These results suggest the existence of the shallow donor consisting of Zn interstitial and/or Zn interstitial-related complex corresponding to a newly appeared 3.33 eV-emission located at ∼40 meV from the bottom of the conduction band.