Study of microstructural evolutions in phosphorus-doped ZnO films grown by pulsed laser deposition

The microstructure of P-doped ZnO films grown on the c-plane sapphire substrate by pulsed laser deposition (PLD) was investigated. ZnO films were highly textured along c-axis with two different in-plane orientations. The textured domain was surrounded by the threading dislocations, resulting in the formation of low-angle grain boundary. It was found that the degree of texture and crystalline quality of P-doped ZnO films decreased with increasing the phosphorus atomic percent. For the microstrain study, X-ray diffraction line profile analysis (LPA) was performed. The 0.5 at% P-doped ZnO film showed much higher microstrain than the 1.0 at% P-doped ZnO film as well as as-grown film, which indicated that the phosphorus in former film was effectively incorporated into ZnO film. X-ray photoelectron spectroscopy (XPS) results showed that the phosphorus in 1.0 at% P-doped ZnO film tended towards segregation, which was well consistent with XRD results.