Investigations of microstructural evolutions after rapid thermal annealing of phosphorus doped ZnO films grown by pulsed laser deposition

The microstructure of as-deposited and rapid thermal annealed (RTA) P-doped ZnO films grown by pulsed laser deposition (PLD) on c-plane sapphire substrates was investigated. Omega rocking curve (omega-RC) and pole figure investigations showed that the degree of texture and crystalline quality of films decreased with increasing phosphorus concentration. X-ray diffraction line profile analysis (LPA) and Warren-Averbach analysis showed that 0.5 at % P-doped ZnO film presented much higher microstrain values than 1.0 at % P-doped ZnO films, which indicated that phosphorus atoms are no longer incorporated into the ZnO lattice for such concentrations. After RTA at 900 degrees C for 3 min, the FWHM values of omega-RCs markedly decreased, indicating a significant improvement of crystallinity. In addition, the change of the conduction type from n to p simultaneously with a decrease of strain suggested that P atoms were incorporated back into the ZnO lattice.