UV and green photoluminescence from spark-processed zinc

Photoluminescence (PL) and scanning electron microscopy studies (SEM) have been performed on spark-processed zinc (sp-Zn). Furthermore, temperature-dependent PL spectra, decay dynamics, and X-ray photoelectron spectroscopy (XPS) have been taken. The area just below the spark-processing electrode is highly fragmented and heavily oxidized. The PL spectrum of sp-Zn peaks at 3.3 eV, that is, in the UV spectral range, and has the characteristics of the band-gap emission of bulk ZnO. Further, the surrounding area of sp-Zn displays a green PL having a maximum intensity near 2.3 eV. The green luminescence band of sp-Zn shows an unusual red shift in the PL peak energy with decreasing temperature. The possible mechanisms causing the observed PL properties of sp-Zn are discussed.