Various types of defect were observed, using photoluminescence techniques, following the reactive ion etching of oxidized B-doped wafers. Their nature depended upon the addition of He to the CHF3/C2F6 etch plasma. In the absence of He, broad bands predominated in the photoluminescence spectra. Two broad lines, at about 0.962 and 1.020eV - with half-widths of about 0.013eV - were the main features after etching in a He-containing plasma. Similar broad lines were detected after the reactive ion etching of B-doped samples in HBr-He plasma, but not after etching in HBr alone. The behavior of the broad lines suggested the existence of an excitonic defect complex that was related to radiation damage-induced intrinsic point defects and to the presence of He in the etch plasma.

H.B.Erzgäber, H.H.Richter, M.A.Aminpur, A.Wolff, K.Blum: Solid State Phenomena, 1997, 57-58, 371-6