Zinc oxide ͑ZnO͒ films were synthesized by thermal oxidation of metallic zinc films in air. The influence of annealing temperatures ranging from 320 to 1000 °C on the structural and optical properties of ZnO films is investigated systematically using x-ray diffraction and room temperature photoluminescence ͑PL͒. The films show a polycrystalline hexagonal wurtzite structure without preferred orientation. Room temperature PL spectra of the ZnO films display two emission bands, predominant excitonic ultraviolet ͑UV͒ emission and weak deep level visible emission. It is observed that the ZnO film annealed at 410 °C exhibits the strongest UV emission intensity and narrowest full width at half maximum ͑81 meV͒ among the temperature ranges studied. The excellent UV emission from the film annealed at 410 °C is attributed to the good crystalline quality of the ZnO film and the low rate of formation of intrinsic defects at such low temperature. The visible emission consists of two components in the green and yellow range, and they show different temperature dependent behavior from UV emission. Their possible origins are discussed.

Room temperature deposition of high crystal quality zinc oxide ͑ZnO͒ films was realized by the filtered cathodic vacuum arc ͑FCVA͒ technique. Detrimental macroparticles in the plasma as byproducts of arcing process are removed with an off-plane double bend magnetic filter. The influence of oxygen pressure on the structural, electrical and optical properties of ZnO films were investigated in detail. The crystal structure of ZnO is hexagonal with highly c-axis orientation. Intrinsic stress decreases with an increase of chamber pressure, and near stress-free film was obtained at 1ϫ10 Ϫ3 Torr. Films with optical transmittance above 90% in the visible range and resistivity as low as 4.1ϫ10 Ϫ3 ⍀ cm were prepared at pressure of 5ϫ10 Ϫ4 Torr. Energetic zinc particles in the cathodic plasma and low substrate temperature enhance the probability of formation of zinc interstitials in the ZnO films. The observation of strong ultraviolet photoluminescence and weak deep level emission at room temperature manifest the high crystal quality of the ZnO films prepared by FCVA. Enlargement of the band gap is observed in the absorption and photoluminescence spectra, the band gap shifts towards lower energy with an increase of oxygen pressure. This phenomenon is attributed to the Burstein-Moss effect.

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Zinc oxide (ZnO) thin-film waveguides with ridge structures have been fabricated on n-type (100) silicon substrates. The deposition of high-crystal-quality ZnO thin films on the lattice-mismatched silicon substrate was achieved by using the filtered cathodic vacuum arc technique. A ridge structure is defined on the ZnO thin film by plasma etching. Room temperature amplified spontaneous emission with peak wavelength at 385 nm is observed under 355 nm optical excitation. The pump threshold is found to be around 0.45 MW/cm2. The maximum net optical gain of the ZnO waveguide is larger than 120 cm−1 at a pump intensity of 1.9 MW/cm2.