ABSTRACT
In the III-V semiconductors, transition elements give rise to deep levels near the centres of the energy gaps. For a long time it was believed that diffusion of transition elements occurred only very slowly so that, for instance, a conducting layer of GaAs could be grown on a chromium-doped substrate without any risk of the chromium entering the layer. A good deal of work has been carried out in recent years with the aim of producing high-resistivity material without resorting to transition elements. An interesting discussion has taken place in the literature concerning the role of manganese in the phenomenon and most of the consequent experimental work has been pursued in an attempt to throw some light on this role. The resemblance between the manganese profiles and those found by other workers for out-diffusion of chromium from GaAs suggested a similar diffusion mechanism for the two elements.
