Formation of self-organized Ta nano-structures by argon ion sputtering of Ta foil: XPS and AFM study

The nano-structured Ta has been prepared by 3 keV argon ion sputtering of the Ta foil. The XPS and AFM studies were carried out on samples sputtered for fluences ranging from 6.0×1015 to 3.6×1016 ions/cm2. The sample sputtered at lowest fluence showed the formation of dimples along with mild ripples which disappeared on further sputtering. After prolonged sputtering, clear ripple formation has been observed with a wave length of about 80 nm. Our XPS results indicated that Ta 4f of the Ta liberated after sputtering is shifted to higher binding energy by 0.5 eV. The Ta2O5 completely disappeared after prolonged sputtering for 60 min, but little amount of sub-Ta oxide (TaOx) is still seen.