Surface modification of ZnO film by hydrogen peroxide solution

The effect of hydrogen peroxide (H₂O₂) treatment on the microstructure and luminescent properties of ZnO thin films has been investigated. Governed by high-resolution transmission electron microscopy and selected-area electron diffraction patterns, the oxygen radicals dissociated from H₂O₂ solution at room temperature and substantially changed the polycrystalline ZnO film into an insulator. In addition, the photoluminescence spectra showed that H₂O₂ solution had nearly no effect on the intensity of ultraviolet emission, whereas it significantly enhanced the intensity of deep-level emission. These observations strongly reveal the fact that the oxygen radicals penetrating into a ZnO film are reasonably speculated to occupy the interstitial sites to form oxygen interstitials Oi or fill the Zn vacancies to form antisite oxygen OZn defects. Because of these extra defects involved, an enhancement of the green light luminescence is significantly promoted in our ZnO samples after handling with H₂O₂ solution. Based on the characteristics mentioned above, our hydrogen peroxide solution treated ZnO film has the potential for applying to the light-emitting diode with metal-insulator-semiconductor structure.