Thin film batteries based on solid electrolytes having a garnet-structure like Li 7 La 3 Zr 2 O 12 (LLZ) are considered as one option for safer batteries with increased power density. In this work we show the deposition of Ta-and Al-substituted LLZ thin films on stainless steel substrates by r.f. magnetron sputtering. The thin films were characterized by XRD, SEM and time-of-flight-secondary ion mass spectrometry (ToF-SIMS) to determine crystal structure, morphology and element distribution. The substrate temperature was identified to be one important parameter for the formation of cubic garnet-structured LLZ thin films. LLZ formation starts at around 650°C. Single phase cubic thin films were obtained at substrate temperatures of 700°C and higher. At these temperatures an interlayer is formed. Combination of SEM, ToF-SIMS and XRD indicated that this layer consists of γ-LiAlO 2. The combined total ionic conductivity of the γ-LiAlO 2 interlayer and the LLZ thin film (perpendicular to the plane) was determined to be 2.0x10-9 S cm-1 for the sample deposited at 700°C. In-plane measurements showed a room temperature conductivity of 1.2x10-4 S cm-1 with an activation energy of 0.47 eV for the LLZ thin film.

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We demonstrate the generation of a persistent conductivity increase in vanadium dioxide thin films grown on single crystal silicon by irradiation with 1 GeV 238U swift heavy ions at room temperature. VO2 undergoes a temperature driven metal-insulator-transition (MIT) at 67 °C. After room temperature ion irradiation with high electronic energy loss of 50 keV/nm the conductivity of the films below the transition temperature is strongly increased proportional to the ion fluence of 5·109 U/cm2 and 1·1010 U/cm2. At high temperatures the conductivity decreases slightly. The ion irradiation slightly reduces the MIT temperature. This observed conductivity change is persistent and remains after heating the samples above the transition temperature and subsequent cooling. Low temperature measurements down to 15 K show no further MIT below room temperature. Although the conductivity increase after irradiation at such low fluences is due to single ion track effects, atomic force microscopy (AFM) measurements do not show surface hillocks, which are characteristic for ion tracks in other materials. Conductive AFM gives no evidence for conducting ion tracks but rather suggests the existence of conducting regions around poorly conducting ion tracks, possible due to stress generation. Another explanation of the persistent conductivity change could be the ion-induced modification of a high resistivity interface layer formed during film growth between the vanadium dioxide film and the n-Silicon substrate. The swift heavy ions may generate conducting filaments through this layer, thus increasing the effective contact area. Swift heavy ion irradiation can thus be used to tune the conductivity of VO2 films on silicon substrates

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