Characterizations of Ga-doped ZnO films on Si (111) prepared by atmospheric pressure metal-organic chemical vapor deposition

Gallium-doped ZnO films were grown on p-Si(111) substrates by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD) using diethylzinc and water as reactant gases and triethyl gallium (TEG) as a n-type dopant gas. The structural, electrical, and optical properties of ZnO:Ga films obtained by varying the flow rate of TEG from 0.56 to 3.35 μmol/min were examined. X-ray diffraction patterns and scanning electron microscopy images indicated that Ga doping plays a role in forming microstructures in ZnO films. A flat surface with a predominant orientation (101) was obtained for the ZnO:Ga film fabricated at a flow rate of TEG=2.79 μmol/min. This film also revealed a lowest resistivity of 4.54×10^-4 Ω cm, as measured using the van der Pauw method. Moreover, low temperature photoluminescence (PL) emission recorded at 12 K demonstrated the Burstein Moss shift of PL line from 3.365 to 3.403 eV and a line broadening from 100 to 165 meV as the TEG flow rate varied from 0.56 to 2.79 μmol/min. This blueshift behavior of PL spectra from ZnO:Ga films features the degeneracy of semiconductor, which helps to recognize the enhancing of transparency and conductivity of ZnO films fabricated by AP-MOCVD using Ga-doping technique.