Bismuth thin films of thickness in the region of 500 nm have been prepared by planar magnetron sputtering onto glass, silicon and GaAs substrates. Electron microscopy of these films reveals that bismuth whiskers grow spontaneously when the substrate is heated to temperatures between 110ºC and 140ºC during deposition and the optimum temperature for such growth is largely independent of substrate. Depositing films under similar conditions using thermal evaporation does not, however, produce the whisker growth. X-ray diffraction has been employed to investigate film texture with temperature and it has been shown that the and has a higher change-over temperature. The whiskers that grow from the film emerge at off-normal angles between 43.3º and 69.2º with a mean of 54±3º. The projected length of whiskers on a 500 nm film on a GaAs substrate shows a wide distribution to a maximum of more than 100 µm. The mean projected length for this sample was 16±1 µm and the diameter is around 0.5 µm. Measurements of the electrical properties of the whiskers at room temperature reveals ohmic behaviour with an estimated resistivity of 2.2±0.2 µΩm. Detailed examination of scanning electron micrographs, eliminates all growth mechanisms except tip growth by a non-catalysed vapour-solid/vapour-liquid-solid method. By depositing thinner films it is shown that this spontaneous growth of whiskers offers a route to fabricate high quality bismuth nanowires of lengths exceeding 10 µm.2

Thin films of bismuth of thickness 100 nm have been deposited onto Si(100) substrates held at 120°C using magnetron sputter deposition. The three-inch magnetrons were operated at DC powers between 30 W and 50 W to give deposition rates between 0.03 and 0.09 nms -1 . Examination of the surface of the thin films using scanning electron microscopy revealed nanowires of diameter 80-120 nm and length between 3 and 16 m emerging from the film. An investigation of the effect of deposition rate found little influence on the nanowire diameter, but indicated that some longer nanowires could be found on the film deposited at the lowest rate. A 20 nm film grown on glass at 110°C shows a nanowire with dimension around 50 nm. Using a relatively higher rate for the first 25 nm followed by a lower rate to 100 nm produced some very straight and regular nanorods. Highlights: 100 nm diameter bismuth nanowires made by sputter-deposition.  Nanowires 3-16 micrometers long.  Diameter not strongly deposition rate dependent in range 0.03-0.09 nms -1 .  Commencing deposition with temporary higher rate gave straight nanorods.

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