Cathodoluminescence on the diffusion front of CdS doped with trivalent metals

Abstract

When CdS crystals are doped with In, Ga or Al by heating in the metal vapour, the trivalent metal diffusion is concentration dependent and a sharp diffusion front is observed. A cross-section of the diffusion specimen under electron irradiation in a scanning electron microscope shows very strong cathodoluminescence, highly localized at and near the diffusion front. The intensity profile across the diffusion front varies with concentration gradient and crystal orientation. The emission spectrum also varies with orientation and distance from the diffusion front and with dopant element but is close to the band-gap energy and is basically exciton and donor-acceptor pair recombination radiation.

SEM analyses of cathodoluminescence in MgO, CdS and GaAs/GaxAl1–xAs crystals

“…These observations arose from co-operative work done with Dr H. Mykura (University of Warwick) and Dr E. D. Jones (Lancaster Polytechnic) who have been studying the diffusion of trivalent metals into CdS (Jones & Mykura, 1978) and the resultant CL with our assistance (Mykura, 1977).…”