The Microstructure And Optical&Electrical Properties Of The Cu₅₀Zr₅₀ Thin Film Metallic Glasses

In this dissertation,Cu₅₀Zr₅₀ binary amorphous alloy system with high glass forming ability was selected as the model materials.Cu₅₀Zr₅₀ thin films metallic glass?TFMG?were deposited on glass substrate by magnetron sputtering.The microstructure and surface morphology of Cu₅₀Zr₅₀ TFMG were characterized by X-ray diffraction?XRD?,Scanning electron microscope?SEM?,transmission electron microscope?TEM?and atomic force microscope?AFM?.The optical properties of Cu₅₀Zr₅₀ TFMG such as refractive index,extinction coefficient,transmittance and absorbance were analyzed by ellipsometry and UV-VIS spectrophotometer.The electrical properties of Cu₅₀Zr₅₀ TFMG such as carrier mobility,resistivity and hall coefficient were measured by Four-probe method.The microstructure,optical and electrical properties of Cu₅₀Zr₅₀ amorphous alloy films under different magnetron sputtering times were studied.Thin film samples were also annealed at different temperatures near the glass transition temperature.and the effect of annealing treatment on the microstructure and optical and electrical properties of Cu₅₀Zr₅₀ amorphous alloy thin films were examined.The Cu₅₀Zr₅₀ TFMG prepared under different magnetron sputtering times were analyzed by XRD and TEM.The results indicated that the XRD patterns of the as-sputtered thin films show single diffuse humps.The TEM patterns indicated that the surface of the film is disordered and the corresponding selected area electron diffraction pattern presents a halo ring,further confirming their fully amorphous structure.The results of film thickness,surface morphology and roughness suggested that during the whole process of deposition,the growth of Cu₅₀Zr₅₀ TFMG can be divided into two stages,as the deposition time prolongs,the surface roughness firstly increases then decreases,at the same time,and the distribution of the clusters firstly shows scattered feature and then becomes continuous.The size of nano-clusters increases gradually with increasing deposition time.The optical properties of the as-deposited Cu₅₀Zr₅₀ TFMG under different magnetron sputtering times were characterized.Results showed that the refractive index of Cu₅₀Zr₅₀ TFMG exhibits anomalous scattering characteristics.That means,the refractive index increases with increasing wavelength,The extinction coefficient shows identical trend.Besides,the film thickness increases whereas film transmittance decreases gradually with sputtering time,showing absorption edge at around 550 nm.With increasing wavelength,the absorption decreases at the early stage of deposition,and then becomes insensitive to wavelengths for the case of sputtering time of longer than 40 min.The electrical properties of as-sputtered Cu₅₀Zr₅₀ TFMG under different magnetron sputtering times were characterized by Four-probe method.As the sputtering time prolongs,carrier mobility firstly increases and then decreases,yielding the maximum at 40 min sputtering time,agreeing with the trend of surface roughness.The hall coefficient of thin film shows clearsize effect.The film resistivity decreases dramatically with increasing film thickness.The conductivity of the film with 200 nm in thickness is worse than that of semiconductor materials.The microstructure,optical and electrical performance of samples after annealing treatment were characterized.The results showed that the annealed films still remain fully amorphous structure.Annealing causes the increase in the nano-cluster size and density of Cu₅₀Zr₅₀ TFMG.The elements distribution of films remains almost unchanged after annealing.The optical properties of Cu₅₀Zr₅₀ TFMG under different annealing conditions were characterized.The results of ellipsometry showed that the annealing treatment caused red shift of the boundary point between "normal dispersion" and "abnormal dispersion".Annealing treatment significantly changed the light attenuation on the film surface.The visible light attenuation is flatten out whereas the attenuation of the long-length light is amplified.UV-VIS results indicate that thin films after annealing becomes denser,without defects such as holes,reducing the film transmittance.The absorption edge still appears at around 550 nm.Meanwhile,higher annealing temperature results in more significant reduce effects.