Argon plasma sputter etching induced defect levels in strained, epitaxial p-type Si-Ge alloys

Argon plasma sputter etching-induced electronic defects in boron doped, str ained p-type Si1-xGex alloys with x = 0 and 0.05 have been investigated by deep level transient spectroscopy (DLTS). Four defects with discrete energy levels, ranging from 0.22-0.55 eV above the valence band, were introduced in p-Si during sputtering. These defects are compared to those introduced d uring electron beam deposition (EB), alpha particle irradiation and Ar ion beam etching. The most prominent defects in Ar plasma etched samples have s imilar electronic properties as a defects detected after electron beam, Ar ion beam etching and alpha particle irradiation. The main defects detected in p-Si was also observed in p-Si0.95Ge0.05. One of the dominating peaks ha s been correlated to the interstitial carbon-interstitial oxygen pair. The decrease in activation energy of this defect for increasing Ge-content from x = 0-0.05 followed the same variation as the band gap in Si1-xGex/Si. Its energy level position relative to the conduction band is therefore the sam e for x = 0 and 0.05 indicating that it is pinned to the conduction band. D efect concentration depth profiling revealed that the main defect introduce d during argon plasma sputtering and Ar ion beam etching is located very cl ose to the surface and is deeper than that detected after EB deposition. (C ) 1999 Published by Elsevier Science Ltd. All rights reserved.