Kinetics of laser-assisted single crystal growth of tungsten rods

The kinetics in laser-assisted CVD of tungsten rods have been investigated as a function of laser power density. WF6 and H-2 were used as reaction gas mixture. At low temperatures and low laser powers densities (P<0.45 MW/cm( 2)) polycrystalline and circular shaped rods were grown. At higher temperat ures and laser power densities, square shaped and single crystalline rods w ere formed. The rods grew out from the surface i.e. parallel with the optic al axis and always in the < 100 > direction. They were characterised by sca nning electron microscopy, energy dispersed X-ray spectroscopy and single c rystal X-ray diffraction.