Cathodoluminescence and polarization studies from individual dislocations in diamond

Abstract

A cathodoluminescence detector attached to a transmission electron microscope has been used to record visible optical-emission spectra from individual dislocations of known type in type IIb diamond over a range of temperatures. The polarization of the emission has also been determined from individual dislocations and this information correlated with the type and degree of dissociation of the dislocations. It was found that the dislocation emission at 435 nm was polarized along the dislocation line (independent of the Burgers vector) and had maximum intensity at 170 K. The emission spectrum was independent of dislocation type, and showed a broad (0·416 eV f.w.h.m.) band. All luminescent dislocations were dissociated, and one non-luminescent dislocation was found which was undissociated within the resolution of the weak-beam technique (∼ 15 Å). Non-luminescent dissociated dislocations were also found. Curved dislocations were less luminescent than straight ones. A one-dimensional donor-acceptor model is suggested as being consistent with all these findings, which rule out several other proposed mechanisms.