Cathodoluminescence study on the tilt and twist boundaries in bonded silicon wafers

We have fabricated artificial tilt and twist boundaries of Si by direct bonding technique. Transmission electron microscopy (TEM) showed that the arrays of edge dislocations were formed at the tilt boundaries, while the square networks of screw dislocations were formed at the twist boundaries according to the misorientation angles. Several peaks were observed in cathodoluminescence (CL) spectra, which may be attributed to the D-lines of dislocation luminescence. Although it is rather difficult to correlate these spectra with certain structures of boundaries, a plausible explanation was given in terms of straightness of dislocation line and dislocation density.