Electronic properties of defects introduced in strained, epitaxial p-type SiGe alloys during sputter etching in an argon plasma

We have used deep-level transient spectroscopy in an investigation of the e lectronic properties of defects introduced in boron-doped. strained p-type Si1-xGex alloys with x = 0 and 0.05, during argon plasma sputter etching. T hese defects are compared with those introduced during electron beam deposi tion of metal contacts and after 5.4 MeV alpha particle irradiation. Four d efect; with discrete energy levels, ranging from 0.22 eV to 0.55 eV above t he valence band, were introduced in p-Si during sputtering. The most promin ent defect, detected in Ar plasma etched samples, has similar electronic pr operties to those of the defects detected after electron and alpha particle irradiation. The main defects detected in p-Si were also observed in p-Si0 .95Ge0.05. One of the dominating peaks has been correlated with the interst itial carbon-interstitial oxygen pair. The decrease in activation energy of this defect with increasing Ge content from x = 0 to 0.05 is found to foll ow the same variation as the bandgap of strained Si1-xGex/Si. The energy le vel position of the defect. relative to the conduction band, is therefore t he same for x = 0 and 0.05 indicating that such a level is pinned to the co nduction band.