Broad defect depth distribution in germanium substrates induced by CF4 plasma

Abstract

The effects of Ar and CF4 plasma on defect formation in Sb-doped Ge substrates were investigated using deep-level transient spectroscopy. Whereas the Ar plasma was found to induce defects with an energy level of 0.31 eV below the conduction band minimum, the CF4 plasma gave rise to many different electron and hole traps. The electron trap with the broadest depth distribution was associated with Sb and interstitials, which extended to a depth of about 3 μm from the Ge surface. These results strongly suggest that the appropriate choice of gas is important during plasma etching of Ge etching in order to reduce plasma-induced damage.