Deposition temperature effects on tungsten single-crystal layer by chemical vapor transport

The growth habits of the {1 1 0} and {1 1 2} crystal planes of large-area tungsten single-crystal layers are investigated. The layers were prepared by high-vacuum chemical vapor transport deposition. The flat-surface {1 1 2} crystal plane grows slower than the rough {1 1 0} crystal plane at 1473 K. The growth rate differences become smaller with increased temperatures (1573–1673 K). The {1 1 2} surface follows a terrace-growth pattern under all conditions. The {1 1 0} surface is characterized by a two-dimensional island nucleus and has a step-flow growth pattern. At 1473 and 1573 K, the structures are column steps and mini-pentahedrons, respectively. The micro-polyhedron structures disappear and are replaced by terrace growth at 1673 K, similar to those of {1 1 2}. The growth habits of the {1 1 0} and {1 1 2} crystal planes are significantly influenced by the movement energy of tungsten atoms on different crystal planes. This energy is affected by deposition temperature.

► Growth rate differences of {1 1 0} and {1 1 2} crystal plane change with growth temperature.
► {1 1 2} surface follows terrace-growth pattern under all conditions.
► {1 1 0} surface follows step growth at 1473 and 1573 K, but terrace growth at 1673 K.
► Adatom movement energy and diffusion activation energy cause crystal plane growth habit change.
► Two competing energies affect the tungsten atom mobility at increased deposition temperature.