Phosphorus Concentration Dependent Microstructure and Optical Property of ZnO Nanowires Grown by High-Pressure Pulsed Laser Deposition

Phosphorus-doped ZnO (ZnO:P) nanowires were grown by the high-pressure pulsed laser deposition process (HP-PLD), where phosphorus pentoxide is used as the dopant source. The morphology, composition, and microstructural changes of ZnO nanowires after phosphorus doping were investigated with scanning electron microscopy, X-ray diffraction spectrum, energy-dispersive X-ray spectrum, transmission electron microscope, and Raman scattering spectrum. Optical fingerprints of ZnO:P nanowires like neutral acceptor-bound exciton emission (3.357 eV, A<sup>0</sup>X), free-electron to neutral-acceptor emission (3.311 eV, FA), and their longitudinal optical (LO) phonon replicas were observed, and their dependence on the phosphorus doping concentration was investigated with room/low-temperature photoluminescence spectra. It indicates that acceptor levels with a binding energy of about 130 meV were formed, and the optimized phosphorus concentration was realized with the ZnO:P<sub>2</sub>O<sub>5</sub> (2 wt %) target.