Preparation of diamond whiskers using Ar/O2 plasma etching

Radio frequency (RF) plasma etching of chemical vapor deposition (CVD) diamond film has been investigated in Ar/O2 plasmas, with an emphasis to elucidate the effects of reacting gas on the fabrication of diamond whiskers. Diamond whiskers were formed on diamond films pre-coated with Al. It was found that diamond whiskers preferentially formed at the diamond grain boundaries. The densities of diamond whiskers increased with O2 / Ar ratio. Whiskers obtained in pure O2 plasma etching were 50 nm in diameter and 1 μm in height. The etching rate was increased by mixing Ar with appropriate volume of O2. Al coated on the diamond surface reacted with O2 to form Al2O3, serving as mask to restrain the etching underneath. Raman spectroscopy measurement confirmed that the whiskers kept sp3 diamond bonding structure after RF plasma etching. The field emission characteristics of the whiskers were also inspected.