Microstructure and electrical properties of ultrathin gold films prepared by DC sputtering

Ultrathin gold films with different thicknesses were prepared by direct current magnetron sputtering technique and analyzed by X-ray diffraction, atomic force microscopy, transmission electron microscopy and temperature-varying four-wire technique. For thicknesses d < 24.1 nm, both Davg {111} and Davg {220} increase rapidly with the thickness. For 24.1 ≤ d ≤ 97.8 nm, Davg {220} increases at a slower rate than before but Davg {111} remains the same. Surface morphology analysis shows that, as the thickness increases, the average particle size changes from 22.1 to 54.3 nm; at the same time, rms roughness decreases to a minimum and then increases. The electrical properties of the thin films from 80 to 300 K were measured. The results show that the temperature coefficient of resistance of the thin films is positive, and increases from 2.2 × 10−4 to 8.5 × 10−4 K−1 with increasing film thickness.