Plasma Assisted Electron Beam Evaporation Of Metallic Zn Preparation Of Nanocrystalline Zno Films Institutions And Optical Nature Of The Study

Zinc oxide (ZnO) is an interesting Ⅱ-Ⅵ wide band gap (3.3eV) semiconductor material with wurtzite structure because of many properties, such as piezoelectricity and photoelectricity. Due to the large exciton binding energy of 60meV, which ensures the high efficient excitonic emission at room temperature, it is regarded as one of the most promising materials for the ultraviolet (UV) and blue light emitting devices. Up to now, many of different techniques such as sputtering, reactive thermal evaporation, spray pyrolysis, pulsed laser deposition, metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) have been used in the preparation of nano-ZnO. But, as for these techniques, it is difficult to prepare stoichiometric nano-ZnO films at low temperature without oxygen plasma assistance due to the larger binding energy of an oxygen molecule (5.16 eV), causing many oxygen vacancies. In this dissertation, nanometer ZnO thin films on Si (100) substrates were prepared by using plasma-assisted thermal evaporation of metallic Zn following by thermal annealing from 300℃ to 500℃ for an hour in oxygen ambient. The structural and luminescent properties of the samples were studied employing X-ray diffraction (XRD), Raman scattering spectra, X-ray photoelectron spectra (XPS)and photoluminescence (PL) spectra. The interface of ZnO/Zn was studied by Raman scattering spectra. At the same time, the source of the ultraviolet emission of ZnO was studied. The experimental results show that we surely can get high quality nano-ZnO thin films at very low annealing temperature (400℃) by using plasma-assisted thermal evaporation of metallic Zn .