A novel electron beam-induced current technique, which used 2 (Schottky and Ohmic) adjacent front contacts, was developed in order to characterize electrically active extended defects in the Si over-layer of SIMOX structures. The results were compared with photoluminescence measurements of the same samples. Electron beam-induced current measurements of n-type SIMOX layers showed that dislocations and precipitates that were present in the over-layer acted as recombination centers. The photoluminescence spectra exhibited dislocation-related emissions whose intensity was related to changes in the density of extended defects, as measured by means of electron beam-induced current techniques, as the wafer was scanned. It was found that p-type SIMOX material contained stacking-fault tetrahedra and pyramids at the upper Si/oxide interface, and threading dislocations that extended across the Si over-layer. However, the photoluminescence emission from these defects was negligible. Thinning of the over-layer by using a sacrificial oxidation process created oxidation-induced stacking faults in the over-layer. These gave rise to strong dislocation-related photoluminescence emissions. It was demonstrated that electrically active extended defects in the Si over-layers of SIMOX structures were also optically active, and that photoluminescence measurements could provide useful insights into the electrical activity of the thin over-layers in these structures.

Y.H.Qian, J.H.Evans, L.F.Giles, A.Nejim, P.L.F.Hemment: Semiconductor Science and Technology, 1996, 11[1], 27-33