On the mechanism of cathodic growth of tungsten needles by decomposition of hexacarbonyltungsten under high field conditions

The mechanism of the recently discovered growth of tungsten needles by vapourphase deposition of tungsten in high electric fields is discussed. The process consists of microneedle growth on a cathode producing an electric discharge by decomposition of hexacarbonyltungsten under high-field conditions. A self controlling mechanism is suggested which draws ions preferably to the top of the growing tungsten needles. The ions can also trigger the deposit of neutral tungsten atoms on the needles. The process is not restricted to tungsten, but can be used also for production of a variety of needles of different metals including alloys.