Atomic layer deposition and characterization of Ga-doped ZnO thin films

Low-resistivity n-type ZnO thin films were grown by atomic layer deposition (ALD) using diethylzinc (DEZ) and H2O as Zn and O precursors. ZnO thin films were grown on cc-plane sapphire (cc- Al2O3) substrates at 300 ∘C. For undoped ZnO thin films, it was found that the intensity of ZnO (101̄1) reflection peak increased and the electron concentration increased from 6.8×1018 to 1.1×1020 cm−3 with the increase of DEZ flow rate, which indicates the increase of O vacancies (VO) and/or Zn interstitials (Zni). Ga-doping was performed under Zn-rich growth conditions using triethylgallium (TEG) as Ga precursor. The resistivity of 8.0×10−4 Ω cm was achieved at the TEG flow rate of 0.24 μmol/min.