Bunched and multi-circularly wrapped carbon nanotubes (CNT) are
observed to grow on alloy substrates based on iron group metals and copper
by a microwave enhanced hot-filament method with a dilute gas of ammonia at
a proper RF self-bias. The grown size of CNTs embodied in the grain sizes of
conducting bulk alloy catalysts such as Cu-Ni, Cu-Fe, Cu-Co, and Cu-Ni-Fe-Co
are controlled by a precursor time of hydrogen plasma etching. Species with
different structural features and homogenization of CNTs samples are
produced crucially attributed to various reactant gases and self-bias
induced by the radio frequency field.