Low-temperature photoluminescence study of ZnO:Ni nanowires

ZnO:Ni nanowires have been fabricated through high-temperature vapor–solid deposition process. The morphology of the as-prepared samples was characterized by scanning electron microscopy. The temperature dependent of photoluminescence spectra was investigated. The low-temperature photoluminescence spectrum at 10–150 K shows that there is a multi-peak emission in the UV region. The multi-peak emissions are attributed to neutral acceptor-bound exciton, free electron to acceptor transition (FA), and first- and second-longitudinal optical phonon replicas emission (FA-1LO and FA-2LO), respectively. With increasing temperature, these bands show different temperature dependences. The FA and FA-1LO bands show a normal redshift with the increasing temperature, while the FX and FA-2LO bands exhibit an anomalous behavior. The origins of these bands and their temperature-dependent shifts are discussed.