Zinc fluoride (ZnF₂) is an insulating wide band gap crystal has been recently demonstrated that this material is attractive for applications as efficient light emitter in the UV.

Crystalline ZnF₂ films of a rutile-type structure were obtained on corning-glass and silicon substrates kept at 100 and 300°C. A film growth along  [110] direction was found.  An amorphous ZnF₂ film was obtained when the substrate was kept at 100°C.

The ZnF₂ thin films were elaborated on silicon and corning glass substrates by using a reactive sputtering with an argon/oxygen/fluorine mixture from a metallic Zn target at 100°C and at constant working total pressure of 100 Pa. The ZnF₂ thin films were investigated by optical transmission, X-ray diffraction (XRD), scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS) and electrical conductivity measurements. The transmittance measurements have shown that all films exhibit high transmittance in the 400–2500 nm range. The averaged transmittance of the ZnF₂ film increased from 80 to 94% upon vacuum-annealing at 300°C for 1 hour (Fig.1). The crystalline structure of ZnF₂ thin films indexed by XRD reveals tetragonal lattice with cell parameters a =b= 4.7034 Å and c = 3.1335 (Fig.2). The RBS measurements reveal that ZnF₂ thin films are almost stoichiometric, with an atomic composition close to Zn(34%) F(66%). The surfaces morphology of ZnF₂ thin films deposited at 100°C, from the scanning electron microscopy images, shows significant changes due to the oxygen partial pressure used during the film deposition. A porous surface consisting of circular craters, with an average diameter ranging between 0.2 and 20nm is revealed. The dark conductivity s_d versus temperature, in the Arrhenius plot, from a ZnF₂ thin films deposited at 100°C and after vacuum-annealing at 300°C for one hour clearly evidenced a very large increase in electrical conductivity, from 10^-10 to 10 W^-1.cm^-1 (Fig.3).

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