Optical characterization of magnetron sputtered p-type ZnO thin films codoped with Ga and As

ZnO films codoped with Ga and As were characterized in detail. It was observed by I–V measurement that the films maintain p‐type characteristics even when the Ga/As ratio is as high as 9. Low‐temperature photoluminescence spectra revealed emissions at 3.36, 3.35, 3.30, and 3.22 eV, which were assigned to the D°X, the A°X, the two‐electron‐satellite D°X, and the DAP transition, respectively. A PL peak also appeared at 3.34 eV in the case of Zn0.96Ga0.03As0.01O and Zn0.90Ga0.09As0.01O films. X‐ray photoelectron spectroscopy indicated formation of Ga–As bonds with increasing Ga concentration, suggesting that the 3.34 eV peak is related to the Ga–As bonds.